After installing Windows XP Service Pack 2, I found folders inside C:\Windows with such names as "$NtUninstallKB810217$". Each holds more than 800MB of files. Can I get rid of them? When you update Windows 2000 or XP, the update program often saves uninstall information to a folder such as the ones you describe. If you're sure you want the update, remove its uninstall folder. To see your PC's saved uninstall folders, open Windows Explorer to C:\Windows (in Windows XP) or C:\WINNT (in Windows 2000); you may need to click Show the contents of this folder. If you don't see any folders, select View, Folder Options, click the View tab, select Show hidden files and folders, and click OK. The Windows Service Pack uninstall is in the folder $NtServicePackUninstall$ (see FIGURE 1). Others are named $NtUninstallKBnnnnnn$ or $NtUninstallQnnnnnn$ (each n represents a digit). If the folder is more than a few weeks old, you can remove it without risk. You then won't be able to remove the associated update--not necessarily a bad thing. Read about updates before you remove their uninstallers at support.microsoft.com/?kbid=nnnnnn ("nnnnnn" is the six-digit number in the folder name). To get rid of an uninstall folder, select it in Windows Explorer, press Delete, and confirm your decision. The uninstall may still be listed in the Control Panel Add or Remove Programs applet, however. To remove it, select the program and click Remove. An error message will ask whether you want to delete the entry from the list. Click Yes.