NOTE: You need administrator level privileges on XP/2000 to run disk defragmenter.

Check your hard drive occasionally to see if it needs defragmenting; running defragmenter can help speed up your system!

Defragging your hard drive is kind of like picking up, organizing by suit and color a deck of playing cards that your 2 year old has scattered all over the floor; this makes it easy to find a particular card in the sorted deck. Disk Defragmenter consolidates fragmented files and folders on your computer's hard drive, so that each occupies a single, contiguous space on the disk volume. As a result, your system can gain access to your files and folders and save new ones faster. By consolidating your files and folders, Disk Defragmenter also consolidates the volume's free space, making it less likely that new files will be fragmented.

With Windows XP and 2000 you can analyze your hard drive first to see if it needs defragmenting (unlike Windows 98, ME - if you have Windows NT there is no built in defrag tool, so you will need a 3rd party tool like Disk Keeper or Norton System Utilities).  If you are a 98, ME or NT user, here's a free defragmentation tool: http://www.majorgeeks.com/download.php?det=1207  ).

Open disk defragmenter, Go to Start, Programs or All Programs, Accessories, System Tools, Disk Defragmenter...highlight your (C:) drive in the Volume Window, then click the Analyze button at the bottom. If your files are less than 11 - 12% fragmented, Windows will tell you that you do not need to defragment the disk.