1. If you have a Windows computer, you must obtain and install all of the following: a reputable antivirus program, a software firewall, a junk-mail filter and an antispyware program. Even if you own a Macintosh (Macs have been unaffected by most of these threats to date), you will still need to turn on your computer’s firewall and employ a junk-mail filter.

2. Upgrade to the latest versions of the leading Windows web browsers, Microsoft’s Internet Explorer 7 and Mozilla’s Firefox 2.0, both of which warn you when a web page you’re visiting appears to be phony. (The new Internet Explorer also has under-the-hood security improvements that close some of the holes plaguing older versions.) You might also consider add-on software, like McAfee’s SiteAdvisor or the new Norton Confidential, which warn about fraudulent sites and, in the case of Norton, also about malicious software on your PC. On a Mac, consider using Firefox 2.0 instead of Apple’s Safari, which, while very good and generally secure, lacks a fake-web-site detector.

3. Never respond to or click a link within any unsolicited email message from a financial institution — even your own — no matter how official it looks. Crooks have become skilled at mimicking logos and typefaces used by banks, brokers and payment services like PayPal. When you click on links within these fake emails, you’ll be taken to web pages that look like the companies’ official sites, even down to the address, but they’ll steal your log-in information. Be especially wary of email from a financial institution that asks for account information or says you must log in at a linked site to address a problem. You can phone the company to see if there really is an issue. Obviously, this caution doesn’t apply to some financial emails, such as confirmations of online stock trades you’ve just executed. But in general, you shouldn’t conduct financial transactions via email or links in email. Instead, go directly to the financial sites you use.

4. Similarly, never act on emails offering stock tips, miracle pills or the chance to earn money by storing millions from overseas in your bank account. Sounds obvious, but in the past these scams might have cost you a little money. Now they may be part of more-damaging identity-theft schemes. Treat such come-ons the way you’d treat a stranger in a bad neighborhood who made such promises.

5. Never, ever download software from a company or web site whose honesty or veracity you’re not sure of. If a site says you’ll need special software to use its features, don’t bite. Even if the software is well known and safe — like RealNetworks’ RealPlayer, Apple’s QuickTime or Adobe Flash — don’t get it from a link provided by a random web page. Instead, visit the Real, Apple or Adobe sites to download it manually.

6. Finally, never use security software offered to you via unsolicited email or a popup window, or that suddenly appears on your PC. Such programs are almost always scams and often install malicious spyware, adware and viruses rather than cleaning them up. In general, stick with leading security brands like Symantec, McAfee, Zone Labs and Webroot. Check the software in the reviews section of PC Magazine or the CNET web site. If it isn’t covered there, it’s probably untrustworthy.

In tacit acknowledgment of IE’s shortcomings, Microsoft is currently mounting a crash effort to update the browser with something called Internet Explorer 7.

But it’s not ready yet. In the meantime, there are a handful of alternative browsers you can use every day instead of IE, on both Windows PCs and Macs — all of them superior to the current version of IE.

One caveat: Some Web sites, especially in the financial industry, have been constructed using proprietary features unique to Internet Explorer. Other browsers mainly stick to industry-standard features, meaning they can’t reproduce every component of these IE-oriented sites. It’s as if NBC decided to produce programming that would work properly only on, say, Sony TV sets. So the bottom line is this: If you are constantly using one of these nonstandard sites, you should continue using Internet Explorer, or at least keep it around for backup.

The best-known alternative to IE is Firefox, made by nonprofit Mozilla. Firefox is issued in nearly identical versions for Windows, Macintosh and the techie-oriented Linux operating system. By contrast, IE runs only on Windows. (Microsoft once made a Mac version of IE, but has discontinued it.) Another excellent choice is Safari, the browser by Apple that comes on every Mac, but has no versions for Windows or Linux. Opera, which comes in Windows, Mac and Linux versions, is also a fine alternative. One more option worth considering is the Windows-only Netscape browser.

These four options share two major characteristics. First, they’re generally more secure than IE. Theoretically, any browser can be attacked and used as a conduit for malicious software that can hobble your computer. Firefox, for example, has been forced to close numerous potential security holes. But IE is the least secure, for several reasons: It was designed in an era when security was less of a concern. Its very ubiquity makes it the favorite target of online criminals. And it uses a Microsoft-only technology called ActiveX that helps Web sites work better, but also allows malicious software to control aspects of the computer. The browsers mentioned above don’t use ActiveX, which is one reason they’re more secure, but it also helps account for their difficulty in handling some IE-oriented Web sites.

The second thing these alternatives have in common is tabbed browsing — the most important advance in browsers in years. This feature lets you open multiple Web sites simultaneously in the same window. Only one page is visible at a time, but the others are live and open behind it. Each is marked by a tab, like those found on paper file folders. To switch from the page you’re viewing to another, you click on a tab. You can also close any page without affecting the others, and if you follow a link on a tabbed page, it usually opens within the same tab. The real power of tabbed browsing comes in when you collect bookmarks (what IE calls “Favorites”) into folders. You can then click just once to open all the bookmarks in a given folder, each under its own tab. For instance, I have roughly 20 technology bookmarks in a folder, and I like to open them all at once in Firefox or Safari, the two browsers I use the most.

Why would you want to use a tabbed browser? First, it saves time. Second, it allows you to easily scan and compare related Web sites. Third, you can open a link in a new tab while keeping the original page open so you can easily return to it. All in all, I can’t imagine going back to Internet Explorer after using a tabbed browser. IE does allow you to open multiple Web pages, but only one at a time and in separate windows, which clog up your desktop and the Windows taskbar. That’s why even Microsoft recognizes the superiority of tabbed browsing and is building it into IE 7. (Note: Microsoft’s MSN online service currently offers an add-on that can bolt a simple version of tabbed browsing onto the current version of IE.)

Another feature the alternatives share, but IE lacks, is a built-in search box that appears right in the toolbar of the browser. This lets you perform a search without using an add-on toolbar or navigating to the home page of the search service.

If all the alternative browsers feature tabbed browsing, built-in search boxes and better security than IE, what are their pluses and minuses? Here’s a quick rundown of the three frontrunners.

– Firefox. This most popular alternative to IE is “open source,” meaning it’s open to improvement by any programmer anywhere. Thus, thousands of add-on features are available by installing free small software modules called “extensions,” which let you do things like download all links on a page with a single click or automatically fill out online forms; there’s even one that lets you view a Web page in IE. Firefox also offers a two-click method for clearing your browsing history and other evidence of where you’ve been online. Finally, its built-in search can be customized to use any popular search engine. That said, Firefox does have some rough edges. Closing tabs with the mouse is awkward the way it’s set up, and the command for viewing your history is illogically placed on the “Go” menu.

– Safari. This Apple browser includes an excellent built-in reader for so-called “news feeds” — summaries of blogs and news sites. It has a “private browsing” mode, which leaves no trace of where you’ve been online, and offers parental controls. It also does a great job of e-mailing entire Web pages, and it can save pages as PDF files, viewable on any computer. But Safari works exclusively on Macs, and its search box works only with Google.

– Opera. This long-established browser is loaded with features, including an excellent zooming capability, and if you have lots of tabs open, Opera can display them on multiple lines so you can more easily read their titles. But while Opera likes to claim it’s “the Fastest Browser on Earth,” in my tests it hasn’t proved itself swifter than Firefox.

You could download any one of these browsers for free today and be on your way to a better Web experience. Or you could wait for IE 7, which is likely to appear in the fall. It promises tabbed browsing, a built-in search box and a bunch of security improvements-that is, everything its rivals already offer.