Over the years, PC World has published hundreds of tips for fixing glitches in Microsoft's Windows operating system. But sometimes, the only cure for a Windows malady is a complete reinstallation. Here's how to reinstall Windows XP.

First, locate the Windows CD that shipped with your PC, along with the CDs for your application software. If you downloaded your antivirus, firewall, or other programs, copy those downloads to a CD or to some other type of removable media. (If your system didn't ship with a Windows CD, your reinstallation files are situated on your hard drive; I'll describe how to access them in just a minute.) Also, dig up the instructions that your ISP sent you for configuring your network settings, and keep them close at hand.

Copy the contents of your 'C:\Documents and Settings' folder (or whichever folder you store your personal files on) to a CD or other removable medium. Then grab any other critical data and back it up. It helps to collect the installers for the latest drivers for your PC's graphics card and other hardware, too.
Ready to Reinstall

Now insert the Windows CD that came with your PC, and reboot your system. If you didn't receive a Windows disc with your machine, the files you need are sitting in a hidden partition on your hard drive. To access them, press the keys indicated on your screen when you reboot, but before Windows loads. The keys differ from vendor to vendor, so contact your PC's manufacturer if you don't see the prompt.

In many instances, the only available option is 'Return the drive to its factory conditi