This is an unique technique for WinXP. We know that it is necessary to wash registry and TEMP files for Win9X/ME/2000 periodly. Prefetch is a new and very useful technique in Windows XP. However, after using XP some time, the prefetch folder can get full of rarely used or obsolete links which can slow down your computer noticeably. My suggestion is: open C(system drive):/windows/prefetch, delete all files (or at least those more than 3 weeks old), reboot. I recommended that you do this every month.
Editor Note: Deleting prefetch files too often (Every reboot) can decrease system performance!
Larry Miller
Microsoft MCSA
http://www.edbott.com/weblog/archives/000743.html
More to the point, what Larry Miller (MCSA) wrote makes sense. The only possible benefit to deleting prefetch files is if you're truly desperate to create space. Maybe you might do this on a cramped laptop, just prior to a defrag, and even then, it wouldn't do much. You probably get more space by deleting your browsers' caches.
"Determine how you want prefetch to run:
*This involves the registry, if you are uncomfortable with this, you should stop here."
move to path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters
On the right side look for a key named: EnablePrefetcher
This decides if and how prefetch runs, here are the value and what they do:
0: Disable
1: Prefetch when an application runs
2: Prefetch on startup or bootup
3: Always Prefetch