dunno if it's okay to post this here, but seeing as how you've mentioned the prefetch and process idle tasks tweaks, i'd really like to know if that works. I have done it myself, [just once so far], but have since came across articles that [kinda convincingly] say cleaning out the prefetch actually impairs performance as opposed to improving it.
check out Ryan Myers[a developer on Microsoft’s Windows Client Performance Team]' blog too:
as for the the ProcessIdleTask API:
in a nutshell: between these articles, they say that the cleaning out the prefetch folder temporarily hinders your system, and XP recreates the files anyway. also, the folder retains only 128 .pf files[doesn't take up too much space, nor cause too much of a diff].
as for calling the processIdleTask from the command line[or even batch files ], it actually keeps your system busy for at least 10 minutes after doing that...
that said, i'm kinda stumped and would appreciate it if you guys could talk about it.