How to do a complete defrag in Windows XP® Page 4
Allow your computer to restart
Go to Start All Programs/Accessories/System Tools/Disk Defragmenter 
In the Disk Defragmenter in the dialog box that comes up select or left
click 
Defragment and allow this process to complete this
could take a long time several hours if it has never been done before. But
if you do it once a month it only takes a few minutes. In the disk Defrag
Mentor Dialog box that comes up click Close.