Vista is the biggest revision to Windows in over a decade. It will be a major change, not only for consumer and corporate Windows users, but for computer makers, software creators and many others downstream.

But what’s in Vista? How will it be sold? And what kind of computer will be needed to run it? Here’s a rough guide to the new Leviathan of the digital seas.

WHY VISTA?

Even after a major overhaul a couple of years back, Windows XP is a security nightmare. With Vista, Microsoft claims to have built in better security from the start, reducing — though not eliminating — the need to buy, learn and maintain add-on security software. The company says better security is Vista’s biggest advantage.

For instance, with the new program you’ll have to type in your administrator ID and password before installing software, to stop malicious software from installing itself silently. And Vista will have built-in parental controls.

Vista’s next big feature is built-in desktop search. Think of this as the Google Desktop search on steroids. From any screen, you’ll be able to start typing a search term and Vista will comb your hard disk for every document, photo, email, song and video that meets that criterion. It should be much faster and better than add-on search programs.

In addition, you’ll be able to save searches in “virtual folders,” which will automatically continue to collect files that meet your search specifications. So if you save a search for “Fountains of Wayne” as a virtual folder and check it a month later, it will contain every e-mail that mentioned the pop band as well as any photos you took at their concert and new songs by the band that you downloaded — even though none of these things existed when you first did the search.

The last major new feature is a rich new user interface. Called Aero, it includes a powerful new graphics system that enables such new extras as transparent windows, animation of certain screen elements (similar to the “funnel” effect Mac users are familiar with when closing a file) and the ability to see reduced, live views of all your running programs at once.

There are lots of smaller changes as well. For instance, there’s a dashboard with small programs (calendar, weather updates and stock tickers, among others) that run quickly, called Gadgets. There’s also new music and video player software; a new built-in Web browser with tabbed browsing; a new, free email program with junk-mail filtering; and a new photo-organizing program.

Many of these features are already available on the Apple Macintosh — some have been for years — but they will seem fresh to most Windows users.

HOW WILL YOU BUY IT?

Like past versions of Windows, Vista will be sold in two ways: The vast majority of people will get it by buying a new PC with Vista preloaded at the factory. That way, they’ll know the hardware and software are compatible. And a small percentage of people, either brave souls or those with PCs too new to replace, will buy Vista in a box and upgrade their computers manually.

Either way, Vista won’t be simple to purchase. That’s because it will come in at least five different flavors, compared with two versions when Windows XP launched in 2001. There will be two consumer versions of Vista, two business versions and one version that includes everything, called “Ultimate.” Also, two current special editions of Windows, the Tablet and Media Center versions, will be folded into some, but not all, of the five Vista editions.

For consumers, the biggest issue will be choosing between the Home Basic and Home Premium versions of Vista, either on new machines or in boxes. Home Premium will include the new Aero user interface along with all the security, search and other features described above. It will also have updated versions of the features currently included in the Media Center and Tablet editions of Windows XP. But Home Premium won’t run on most Windows PCs currently in the hands of consumers, and it also won’t run on new, low-end PCs. That’s because it requires hefty hardware to work right.

Most current PCs, and all the bargain-priced new ones preloaded with Vista next January, will be able to run only Home Basic, which is a stripped-down version of Vista. Microsoft insists that Home Basic will have the same security system and search features as Premium, but it won’t include the new Aero user interface and will probably lack some other features. In essence Home Basic will look and feel like a modestly improved version of Windows XP, even though Microsoft says there’ll be major improvements under the covers.

Power users, and those who want every option just in case, may go for the Ultimate version of Vista. It not only will roll up everything in the consumer and business versions, it may also have some added bells and whistles. Microsoft hasn’t announced prices yet.

WHAT HARDWARE WILL YOU NEED?

The stripped-down version of Vista, Home Basic, will run on fairly routine PCs, albeit ones with plenty of memory.

The Premium and Ultimate versions will likely require at least a midrange model or a high-end configuration.

Microsoft hasn’t officially released the recommended hardware specs. But I expect the company to recommend 512 megabytes of memory for Home Basic and a gigabyte of memory for Premium. Based on past experience, I advise doubling those amounts, to a gigabyte of memory for Basic and 2 gigabytes for Premium.

Another crucial hardware factor will be the computer’s video system. Basic Vista can run on any graphics hardware that creates a screen resolution of at least 800×600. That covers most bargain computers with graphics chips that are integrated with the machine’s motherboard and which share main memory. But Premium and Ultimate will run best on machines with a full-blown graphics card and dedicated video memory of at least 128 megabytes.

You will be able to run Home Basic on the slowest processors available, but for the better versions of Vista, you’ll need a processor running at a speed of at least 1 gigahertz. I would opt for as fast a processor as you can afford and for one with two “cores” rather than one. (A dual-core processor is essentially like having two processors on one chip.)

Vista will also support so-called 64-bit processors, which can gulp down more information than current machines. But I wouldn’t worry about that for now, unless you’re a power user. There’s very little 64-bit software available for consumers.

Vista may not be something to leap into right away. You may want to wait a while to see about defects and, especially, to see if it seems more secure, as promised.

But what about the other major function of a laptop-viewing and editing Microsoft Office documents? Well, it turns out you can do that, too, on these devices, at least to a point. Currently, you can read Word, Excel and PowerPoint files, as well as Adobe PDF files, on certain handhelds; you can even edit them and synchronize the changes back to a PC.

Here’s a look at how that’s possible, on the three most popular types of smart phones and PDAs in the U.S.: those powered by the Palm operating system, those powered by the Windows Mobile operating system (formerly known as Pocket PC), and the BlackBerry, which uses both hardware and software from RIM.

First, make sure your device has lots of storage capacity, either in internal memory or on a removable memory card, if your device can accept them. (The Treo, the iPAQ and most other devices running Windows Mobile software can; BlackBerry models cannot.) You will need that room to store your Office documents.

Second, I strongly advise those wanting to edit documents to buy a phone or PDA with a full keyboard, rather than one that relies solely on handwriting recognition or a phone keypad. The software for viewing and editing documents does work on devices without a keyboard, but unless you just want to read documents, the process is painful on these models.

You might think that the devices running Windows Mobile software would do the best job of handling Microsoft Office documents because both systems are made by Microsoft. Or you might imagine the BlackBerry was tops at this task because it is bought mostly by corporate computer departments, where Microsoft Office is the application software of choice. But in fact, the best devices for viewing and editing Office documents are those using the Palm operating system, such as the Palm Treo 650. That’s because of a helpful third-party program, Documents to Go, from DataViz, which is packaged with many Palm devices, including the Treo.

Next best are the Microsoft-powered phones and hand-helds, which come with built-in mobile versions of Word, Excel and PowerPoint. Bringing up the rear is the BlackBerry, which can display Word, Excel and PowerPoint files when sent as e-mail attachments, but doesn’t let you edit or synchronize them with a PC.

Palm OS devices. The best smart phone on the market is the Treo 650, produced by Palm and powered by the Palm operating system, which is made by a separate company called PalmSource. While the Palm software lacks the built-in capability to read or edit Office documents, the Treo comes bundled with Documents to Go, which can import and open Microsoft files in their native formats without downsizing them to some special “pocket” version. It also allows you to edit, or even create, these types of documents and synchronize your changes with versions on your PC.

You can get the documents into your Treo or other Palm device either by receiving them as e-mail attachments or via synchronization with your PC. Documents to Go includes a computer program that performs this document synchronization; I use it often on my Treo 650. It displays documents in their actual fonts, including colors and attributes like underlining, bold and italics. Indents and spacing are also preserved. The Treo 650 doesn’t support different font sizes, and it doesn’t include a spell checker. Documents can be opened from, or stored to, either the device’s internal memory or a memory card. You can also zoom the screen to show more or less of the document, especially important with spreadsheets, which often sprawl across the page and can be hard to read when resized to fit entirely on the small screen. PowerPoint files can be edited and synchronized only if you are using a Windows PC, though they can be viewed if you are using a Macintosh.

In my tests over the years, Documents to Go performed flawlessly, better than the built-in mobile Office programs on Windows-powered handhelds. In addition to being bundled with the Treo and some other Palm devices, Documents to Go is available for independent purchase, in several versions, for $30 to $90, depending on features. There are also versions for smart phones that use the Symbian operating system, including models from Nokia and Sony Ericsson. You can find information and purchase Documents to Go at www.dataviz.com [http://www.dataviz.com].

Windows Mobile devices. There are two kinds of devices powered by Microsoft’s Windows Mobile software. Some are confusingly named “smart phones,” though they generally lack keyboards and some key software capabilities, including the ability to edit Office documents. Others are full-featured handhelds, including some with keyboards, such as several of HP’s iPAQ models, the new Samsung i730 phone and the very latest and greatest Windows Mobile device, the Treo 700w.

The new Treo is the first device built by Palm to eschew the Palm operating system for Windows software. While it’s mainly aimed at the corporate market and, in my view, isn’t as good as the Treo 650, the 700w is probably the best Windows Mobile device. On the new Treo and others, you can read, edit and create Word and Excel files, and synchronize them with your PC. You can view PowerPoint files, but not edit or create them.

As with the Treo 650, you can get these documents into your device either by receiving them as email attachments or by copying them from a PC.

While the mobile Office programs on the Windows devices work okay, they aren’t quite as good as Documents to Go, in my experience. For instance, in a recent test I opened a simple Word document on two Treosa 650 running the Palm OS and Documents to Go, and a 700w running Windows Mobile and its built-in Office Mobile programs. Documents to Go opened the program perfectly in its Times New Roman font and sized it so the words were distinct, and the formatting was preserved. The Word Mobile program in Windows Mobile displayed the document in a different font and in a size that screwed up the formatting. And while Documents to Go allows you to create and edit PowerPoint files, Windows Mobile doesn’t.

BlackBerry. The BlackBerry can view Office documents when received as e-mail attachments, but the function is pretty primitive. You can’t directly import documents or synchronize them with a computer. And you can’t create or edit them, even though you have a full keyboard at your disposal.

There is a third-party program for the BlackBerry that claims to allow editing, creating and synchronizing of Word and Excel documents, but not PowerPoint files. It’s called eOffice, made by a company called DynoPlex, and it’s available in versions ranging from $120 to $200 at www.dynoplex.com [http://www.dynoplex.com].

I wouldn’t want to write a long report on a Treo. But in a pinch, I could have written this column on one. And editing a document like this is a breeze. So you really can leave that laptop at home, at least some of the time.

But as slick as it is, Apple’s latest baby isn’t the only path to portable digital video available to consumers. Others got there first. All, including the new iPod, suffer from a dearth of legal downloadable content, but that has begun to change as Hollywood and the television networks seem willing, suddenly, to sell individual episodes of television series.

Here’s a quick guide to some leading portable video devices.

Old reliables: All the new video gadgets should be measured against portable DVD players and laptops with DVD drives. The portable players combine relatively large screens with thin, light designs and low prices. The laptops are larger and pricier, but their advantage is that many people carry them anyway for other purposes. And both have a vast library of cheap content to draw from: DVDs. The downside is that you have to lug along a selection of disks.

Portable media centers: These are gadgets that are smaller than a laptop, but larger than an iPod. They use Microsoft software that mimics the nice user interface in its Media Center version of Windows. Leading examples are the Samsung Yepp PMC and the Creative Zen PMC, both of which cost $500, which is more than even the priciest video iPod. They have larger screens than the iPod, but smaller storage capacity. Little legally downloadable content is available for the PMCs, but users can transfer to them TV programs they have recorded on high-end Media Center PCs.

Sony: The new PSP, or PlayStation Portable, from Sony, has a large, bright screen that does a great job showing videos, even though it is primarily a game machine. This slick, black $250 gadget is handsome, but unlike the iPod, it’s too large to carry in a pocket. Also, getting video into the PSP is clumsy and expensive, mainly because it lacks either a hard disk or a standard DVD drive. You have to buy movies on special, small copy-protected disks. And if you want to transfer videos from a computer, you have to buy a high-capacity memory stick.

Archos: This small company has been a pioneer in handheld video and makes several models, in a wide variety of sizes and capacities, that cost from $500 to $800. In general, Archos buyers have been early-adopter techies and videophiles willing to do what it took to collect video clips and move them onto the Archos gadgets. But the company is now going mainstream, through a deal with EchoStar, the satellite TV firm. EchoStar will sell three Archos models, rebranded as PocketDISH players, that can copy and play back TV shows recorded by EchoStar set-top boxes with digital video recorders inside. The PocketDISH players range from $300 to $600.

iRiver: The Korean maker of portable music players has just introduced a tiny video player, smaller but thicker than the video iPod, called the U10. It’s a handsome gadget with a clever user interface: You select functions by pushing on the edges of the screen. But it has a meager storage capacity, only a gigabyte, in a top-of-the-line model that costs $250, just $50 less than a video iPod with a larger screen and 30 times the storage.

Apple: The video iPod, which Apple calls simply the iPod, comes in two models: a $299 version with 30 gigabytes of storage and a $399 model with 60 gigabytes. Like all iPods, it is beautiful, easy to use, and it’s thinner and lighter than the prior generation. Short videos look great on its screen. Apple is selling episodes of two hit TV shows, Desperate Housewives and Lost, for $1.99 each. Again, content for all these gadgets is sparse today. But as the availability of legal video downloads grows, so will the rationale for buying a portable video player.

The daunting security problems that have plagued Windows have also prompted many of its users to take a serious look at the Mac. This trend has been further reinforced by the “iPod halo effect,” in which Windows users who own and love Apple’s iPod music players are willing to consider the company’s other products. As a result, Mac sales, while still relatively small, have been growing much faster than overall personal computer sales.

Are you among the PC majority considering a switch to the Mac? Then you probably have some important questions.

How do Macs compare in quality with Windows PCs?

I believe that, at the moment, Apple makes the best computers, and the best operating system, for mainstream consumers doing typical tasks — e-mail, Web surfing, office — productivity functions such as word processing and presentations, photo organizing and editing, playing and collecting music, and editing home video.

Of all the major computer makers, Apple is the most focused on consumers and small businesses. Most make the bulk of their money, and take most of their cues, from the information-technology departments of large corporations.

Apple’s iMac G5 consumer desktop is, in my opinion, the single best home computer on the market. Its PowerBook laptops are among the top portables.

Do Macs run Windows and Windows software?

No: Out of the box, Macintosh computers run only Apple’s own operating system, called OS X, and software written by Apple and other companies that is designed to run on OS X.

You can rig a Mac to run Windows and Windows programs by installing a special, $250 Microsoft program called Virtual PC, which creates a virtual Windows computer inside the Mac. But I don’t recommend this for frequent use, because the faux Windows computer it creates is relatively slow and is susceptible to the same viruses and spyware as a real Windows machine.

How does Mac software compare with Windows?

The Mac’s OS X operating system, the latest version of which is called Tiger, is far better than Microsoft’s aging Windows XP and already boasts many of the key features Microsoft plans to include in its 2006 version of Windows, called Vista. And the Mac comes with an excellent suite of free software that’s generally superior to comparable Windows programs that cost extra.

Out of the box, the Mac has better photo, music, video and DVD — creation software than any Windows computer I’ve seen. It has a better free email program and Web browser than Windows does, a better free word processor and much better search capabilities.

About the only software a typical consumer would have to buy for a new Mac is the Mac edition of Microsoft Office. It includes versions of Word, Excel and PowerPoint that are very similar to their Windows counterparts, and a program called Entourage that is different from Microsoft Outlook but performs the same functions.

Are Macs more secure than Windows PCs?

Yes. Since the OS X operating system came out in 2001, there has never been a report of a successful virus for it — that is, a virus that has infected numerous computers, and spread from computer to computer, outside of a lab. And there is little or no known spyware for the Mac. By contrast, there are tens of thousands of viruses for Windows and untold numbers of spyware programs. Just as regular Windows programs can’t run natively on a Mac, none of these malicious Windows-specific programs can run on a Mac either.

The Mac isn’t invulnerable, but it has better built-in security than Windows, and such a small market share that virus and spyware writers haven’t targeted it yet. As a result, most Mac users have been able to dispense with running the morass of security software that Windows users must employ.

Are Mac files compatible with Windows files?

Yes. Unlike older models, the current Macs have been specifically designed for compatibility with Windows PCs. The Mac OS and software can handle, without translation or conversion, all of the common types of files you use on a Windows PC. You can copy to a Mac all your pictures, MP3 music files, text files and Adobe PDF files, and they will open right up in Mac programs. There are also free Mac versions of the Real Player and Windows Media Player, and of Adobe Reader.

Microsoft Word files also can be opened, edited and created in Apple’s free, built-in text editor. And if you buy Microsoft Office for the Mac, all Office files, including Word files, Excel files and PowerPoint files, can be opened, edited and created on the Mac. Office files created on the Mac can be opened and edited in Windows Office, and vice versa.

Some specialized files created by particular programs, like database files or financial files, won’t be usable. For instance, the Mac version of Quicken is quite different from the Windows version and uses a different file format.

For occasional use of these programs, you can install Virtual PC.

In addition, nearly all keyboards, mice, monitors and printers made for Windows computers can be used with a Mac, if they connect via the industry-standard USB or FireWire ports. Macs can also share networks with Windows PCs and even look into the hard disks of Windows computers, and vice versa.

Is there anyone who shouldn’t consider a Mac?

Yes. Serious game players should stick with Windows PCs, which are much better game platforms and can run many more game titles. People who use specialized software or custom corporate software for which there isn’t a Mac equivalent should stick with Windows. While the Mac has rich offerings in mainstream software categories, it has only a fraction of the niche software and specialized business software that Windows does.

Also, you should stick with Windows if your home computer choices are dictated by your company’s IT department and the IT department is ignorant of or hostile to the Mac, as so many are. Although modern Macs are designed to access corporate Windows networks, and many do, if your IT department won’t help you with the transition, it’s not worth the headache to switch to the Mac.

Ten years ago, when Apple was stagnant and its products troubled, I recommended that consumers shun the Mac. If Apple’s quality and innovation slip, I might revert to that position. But for now, the Mac is the best computer, with the best operating system and the fewest security problems, for average consumers.

There are three main reasons for the success of iTunes. First, it is tightly tied to the iPod, Apple’s wildly popular portable music player. The only legal downloads of major record label songs that the iPod can play are those sold by iTunes. Second, it is well-designed, works identically on the Macintosh and Windows PCs, and is easy to use. Third, its restrictions on the use of downloads are comparatively liberal: You can copy each purchased song to up to five computers and to an unlimited number of iPods and burned CDs.

For these reasons, nobody else has been able to gain any traction in the legal market by copying Apple’s model, and that includes companies as formidable as Microsoft, Sony and Wal-Mart.

So Apple’s music competitors are trying something else: a whole different model for distributing music legally. Led by the reincarnated (legal) version of Napster, by RealNetwork’s Rhapsody service and by Yahoo’s new music service, these companies are hoping to win by renting music to consumers rather than selling it to them.

In the download model championed by Apple, the music service functions like a physical record store. You choose a track, pay 99 cents, and you own it. As long as you abide by the restrictions, which are designed to thwart mass copying by pirates, the song will play anywhere you want to hear it forever, with no further payments required.

However, those 99-cent downloads can mount up fast. If you tried to fill up even the lowest-capacity full-size iPod-which holds 5,000 songs-with tracks purchased from iTunes, it would cost you nearly $5,000. (Granted, most people start with music they already own when loading a new iPod.)

By contrast, the rental services work on a subscription model. You pay, in most cases, $180 a year, or $15 a month, for the right to download as many songs as you want for use on computers and portable players. And the newest rental contender, Yahoo, has slashed those fees to $60 a year, the equivalent of just $5 a month. That means you could fill up a 5,000-song portable player for just $60 a year.

This rental model has attracted a solid audience, but it is nowhere near as popular as iTunes — not even close. That may be because the rental model is far more complicated and restrictive than iTunes, and has several big downsides.

The biggest problem with renting is that if you stop paying your subscription, even for one month, all the songs you’ve ever downloaded — going back years — will become inert and unplayable. Rental song files are rigged with computer code that requires a monthly digital confirmation the renter is continuing to pay. Without that, the song files die.

An iTunes user could pay $500 to acquire 500 individual songs (buying whole albums is somewhat cheaper) over two years, and those songs are always hers and will always play. By contrast, a Yahoo user might download 500 rental songs over two years for just $120 in subscription fees, but the songs will become unplayable unless she pays hundreds or thousands more in subscription fees over many years, even if the fees rise.

Also, the rules for rental songs are more restrictive than for owned downloads such as Apple offers. At Yahoo, for example, you can store each song on only three computers, versus Apple’s five. And you can install each song on only two portable devices, versus an unlimited number at Apple.

Oh, and you can’t burn rental songs to a CD. To get a nonexpiring, CD-burnable, iTunes-type song from a rental service, you have to pony up 79 cents a track over and above your monthly or annual subscription fee.

Furthermore, rental services are far more complicated than iTunes to operate. At the Apple service, every song is a 99-cent download you can own, but at rental services, there are different kinds of songs. Some can be both rented and purchased (for that extra 79 cents each); others can be either rented or bought outright, but not both. Some songs can only be “streamed” — that is, they can be played directly from the Internet, but not downloaded, even on a rental basis. And some can be rented, but not streamed. You get the picture.

Not only do the rental services feature different kinds of songs, but they feature different kinds of customers, with different privileges depending on how much they pay per month or per year. Some rental plans allow you only to stream songs. Others let you download, but only to store the songs on computers, not portable players. The costliest plans — $15 a month at most services, $5 at Yahoo — allow you to stream, download and store the music on both computers and portable players.

Another huge downside of the rental services is that the songs they rent — and even the ones they sell outright for the extra 79 cents — cannot be played on the world’s best and most popular portable player: Apple’s iPod. That’s because the rental-service songs are encoded in a format owned by Microsoft, Apple’s rival, and Microsoft software is required to play them on a portable player. Apple won’t build the necessary Microsoft compatibility into the iPod.

So rental users are stuck with inferior portable players that don’t sell well and thus don’t attract the huge number of accessories available for the iPod. Apple estimates the iPod has about a 75 percent share of the total U.S. portable player market, with the next-highest brand at just 5 percent. There are over 500 accessories sold for the iPod, such as customized car mounts and leather cases, and just a few for other players.

Given all that, why would anyone use a rental service? Well, the rental model is better for people interested in sampling a wide range of music without a large out-of-pocket expense. That might make it attractive to curious but cash-poor students, for example. The rental services also have many more “community” features than iTunes does, features that allow friends and families to share music recommendations, see what others are listening to and discuss music. So they may be better for people who view music as a social activity.

But for most people, it’s no contest: Right now iTunes and the iPod are the better choice in digital music.

Back in 2001, the iPod was the first widely sold product to use one of these little hard disks. With a diameter of just under 2 inches, it’s smaller than the hard drives used in most laptops, yet it can hold up to 60 gigabytes of data, or around 15,000 songs. The midsize iPod Mini uses an even smaller version, albeit with decreased capacity. It’s just an inch in diameter but holds up to 6 gigabytes of data, enough for around 1,500 songs. (The lowend iPod Shuffle doesn’t use a hard disk, and it holds relatively few songs in its memory chips.)

But now these little hard disks are migrating to other devices — including cellphones and personal digital assistants — made by other companies, giving these gadgets some of the iPod’s magical combination of diminutive size and expansive capacity. And since these devices can play music, along with the various other functions they perform, they could soon become a challenge to the iPod.

For example, two big cell phone makers, Samsung and Nokia, have designed music-playing phones with small internal hard disks that hold a few gigabytes of data. Samsung’s hard-disk model is sold so far only in Korea, but could make it to the U.S. by the end of this year. Nokia’s will be rolled out late this year, probably first in Europe.

By late 2006, I expect Americans to have numerous choices in hard-disk cell phones.

The first PDA with a hard disk to be offered in the U.S. came out in May. It’s the $499 PalmOne Life-Drive. PalmOne sells the LifeDrive — with its large color screen and 4GB hard disk — as a portable way to store and view or play back music, videos, photos and office documents. It also features the usual Palm calendar, contact and notes functions, and with its Wi-Fi and Bluetooth wireless networking, it can surf the Web and send and receive e-mail.

The LifeDrive is bulky — much larger and heavier than an iPod Mini with the same size hard disk. And it isn’t a great music player — it has touch-screen play, pause, fast forward and reverse rather than proper buttons, and it doesn’t come with headphones. But it could be the start of a trend for PDAs, since it should be possible to wedge a similar hard disk into a smaller device.

More likely, the bigger threat to the iPod will come from iPod-enabled cell phones. People have to carry their phones anyway, and some already offer music-control buttons and headphones. So if your phone can hold thousands of songs, why carry around a second, separate music player?

Of course, phonemakers still have to prove they can design music-playing phones that are as simple, elegant and cool as iPods. But that could happen.

Little hard disks could also revolutionize digital cameras, allowing photographers to store thousands of shots without lugging around a laptop, although I know of no camera to date that has a hard disk.

Another trend: Small hard disks will likely shrink even more. Already, there’s a company making one with a diameter smaller than an inch. But mini hard drives may also face a challenger of their own — high-capacity memory chips. The chips have tended to be costlier per unit of storage than the disks, but over time they could get competitive. Prices are dropping fast, and chipmakers are working on memory cards, like the one in your digital camera, that are capable of storing over 10 gigabytes.

For now, though, keep your eye on the little hard disk that powers the iPod. It may be powering lots of gadgets soon.