A program called Diskeeper by Executive Software.
This program overwrites the default windowsXP defrag with its own far superior defragmentation program.
* Set CPU usage priority
* Boot-time defragment option
* Logging
* Chose to not defragment certain files/folders
By far the best feature is 'Set it and Forget'.
Schedule the program to defragment your computer automatically,
* With Smart Scheduling, you no longer have to decide how often to defragment your disks—Diskeeper will automatically determine the optimum defragmentation schedule for each of your disk volumes and adjust it accordingly.
* Exclusion times where diskeeper won't run
* Daily/weekly/weekends...
* Scrrensaver Mode: Set diskeeper to run behind your screensaver, can set prioroty to low to work along side any other research/cpu hungry screensaver program (folding@home...)
http://www.executive.com/defrag/defrag.asp