Each time you run an application, a few small files are created (and often not deleted) that are a partial record of the work you’ve done to let you quickly access data and sometimes perform an exact same action faster than you did before. Additionally, when you update a program or completely remove an application, the application may not remove the “temporary” files it creates during the installation and removal process. As orphaned files accumulate, your computer may access data slower because the junk files make it more difficult for your PC to locate specific files. Windows Disk Cleanup is a utility that removes the useless files.

To run Disk Cleanup in WinXP or Vista, click the Start button, select All Programs, choose Accessories, select System Tools, and click Disk Cleanup. In Vista, you’ll need to select a specific drive for Windows to scan. When you run the utility in WinXP, it will simply search the drive where Windows is installed. Note that if you want to use Disk Cleanup in WinXP on another drive, such as a portable hard drive, press the Windows logo and E keys simultaneously, right-click the drive you want to scan, select Properties, and click the Disk Cleanup button.

After Disk Cleanup has scanned the drive, the utility will generate a Files To Delete list, which is a categorized inventory of the junk files on your PC. To select or deselect a category, click the checkbox next to the listed option. Once you’ve selected files to remove, click OK and select Yes. After running Disk Cleanup, you should also use the Disk Defragmenter utility to arrange the data on your hard drive for fastest access. WinXP and Vista users can choose Start, select All Programs, click Accessories, choose System Tools, and click Disk Defragmenter.

Regularly defragmenting a hard drive is also a good way to ensure peak performance. In Vista, the Disk Defragmenter utility is automatically scheduled to occur every Wednesday at 1 a.m. If you don’t leave the PC on at night, open Disk Defragmenter and click the Modify Schedule button to select a better time for automatic defragmentation. Note that performing tasks while the reorganization tool is running may make your applications seem sluggish, and you may prefer to schedule it at a time when you won’t be using demanding applications.

Unlike Vista, WinXP does not schedule defragmentation, but you can use the Schedule Tasks utility to automate the process. To do so, click Start, select All Programs, choose Accessories, select System Tools, and click Scheduled Tasks. Double-click the Add Scheduled Task icon, click Next, and then click Browse. Select the drive where Windows is installed (likely the C: drive) and navigate to the WINDOWS\System32 folder. Locate Defrag.exe and double-click it. Follow the Scheduled Task Wizard instructions to set up a suitable time for Disk Defragmenter to run.