Whatever you use your PC for, chances are you can do it more productively, whether you're a computer guru or newbie. And you can do it without spending a dime with free software programs and Web services. Nerds may not all be saints, but there's a long history in the computer world of programmers sharing their work for free. Today, you can still download "freeware" from the Internet. Typically, these are small programs released by developers to the public without charge, sometimes it's out of sheer generosity. Some developers have other no less valid motives such as promoting their consulting business or offering a limited free version of their work in the hope that users will upgrade to a beefed-up pay version.

Typically, programmers prohibit you from selling their program or altering its source code. But a growing number of "Open Source" adherents, following the example of the Linux operating system, release their program's source code to the public over the Internet without restriction in a worldwide collaborative effort to create the best possible product. The Open Source Initiative at www.opensource.org, offers further information about this phenomenon.

On the Web, some of the e-commerce companies are moving beyond the advertising-only model and are now charging for their services in a scramble to survive the dot-com shakeout. But most Web-based services remain free. All this seems in antithesis to our market economy and to the very nature of capitalism, and it flies in the face of common sense notions of how to profit from your labor. How well can you be doing if you're pricing your product at zilch? And, from a consumer perspective, how valuable can something be if doesn't cost anything? It turns out that the best of the free software programs and Web services nullify the notion that there's no such thing as a free lunch. These are excellent tools. But, as with anything, there is a potential downside here.

One negative with a free program is that you probably won't receive the same technical support as with a pay program (though good tech support with pay programs is never a certainty). Another negative, which is true any time you tweak a PC, is the risk that something will go wrong, which in a catch-22, can necessitate tech support.

One way to protect yourself with Windows-based PCs is to make back-up copies of two files that together comprise part of the inner workings of Windows called the "Registry." You can do this with the help of software, though it's simple enough to do manually. If you're using Windows 95, Windows 98 or Windows Me, copy the files system.dat and user.dat in the Windows folder to a Zip or similar removable drive, a back-up tape or another folder on your hard disk. In case your system does get corrupted, which is possible but highly unlikely with any given tweak, you can correct things in most cases by simply copying these Registry files back to the Windows folder. If you're using Windows NT or 2000, you should use the Backup utility included to back-up the Registry and, if need be, to restore it.

Here's a sampling of the best free productivity-enhancing computer tools: