Today's "older" computers are perfectly capable of accommodating the needs of young PC users, and they're excellent machines for playing educational CDs, small multimedia files, or games downloaded from the Internet. And don't forget the most important role they play in a child's homework-clad life: A simple encyclopedia CD on a used computer makes excellent research tool (not to mention a rather fancy calculator! Double-clicking one of these kinds of files will open up a window that displays the contents of the archive. In most cases, you can double click a file inside this window to use it, or you can select it and drag the file to a folder to view later. Depending on how you elected to install Winzip or StuffIt, you may be able to right-click a . You could make a batch file that loads up your favorite websites at once for example, or you could make a batch file that fills your desktop with the most important applications for the day. To do so only requires a little knowledge about the locations of these applications. Let's say that every day we need to load up the Yahoo web browser, Microsoft Word, and then the calculator that comes with Windows. We tried to upgrade one of our Windows 98 machines to Windows XP, but we were cautioned that the former may not be hardware compatible with XP technology. Apparently, the Windows XP operating system requires components that weren't developed at the time Windows 98 was distributed and if we were to install Windows XP on this machine anyway, the new operating system would look for hardware that the computer didn't have. Fortunately you have this article to guide you through some of the most common extensions that you'll run into. But before you can see file extensions, you need to turn them on. From Windows Explorer, click on the "Tools" menu, and select "File Options." Click the "View" tab and then uncheck the box next to "Hide file extensions for known file types. Be safe and scan each and every file you download from the Internet or receive through email regardless of where it came from. 4. Create a barrier between your computer and prying eyes. Anti-virus/anti-spyware programs are only effective after the effect. But you can prevent identity theft from occurring by installing a firewall.