Your system is at its best performance when it is brand new because at that time it does not contain any unwanted information. Your PC starts filling up when you start installing additional programs, creating and storing new files, browsing the web and downloading emails. Over time, a lot of unwanted files and programs collect on your PC and unnecessarily slow it down. Therefore, your first step to make your slow PC run faster would be to get rid of this unwanted stuff. You can do this by using the Disk Cleanup tool. In Windows XP, you can access this tool from Start > All Programs > Accessories > System Tools > Disk Cleanup.

The Disk Cleanup tool is your one stop tool to compress old files, empty the recycle bin and get rid of unwanted temporary internet files, cookies, downloaded program files, and other temporary files. If you open the More Options tab on the Disk Cleanup dialog box, you may use the options available on this tab to uninstall unwanted Windows components, applications, and old System Restore snapshots.

Defrag the Hard Disk. As your PC gets older, files on it start getting fragmented as parts of the same file are physically stored in multiple locations on the hard disk wherever space is available. This not only increases the load on the hard disk head because it has to move all over the disk to read a single file, but also slows down your PC. So, after you have used the Disk Cleanup tool to remove unwanted files from the disk and freed up space on it, use the Disk Defragmenter tool to defrag the hard disk and make it contiguous.