Here's a fantastic website for optimizing Windows 2000 thru Vista and a lot more.

 

http://home.comcast.net/~SupportCD//index.html

 

I've searched these forums and didn't find a post about this website so there is now.

 

Here's the link from the index above to the Optimize XP Guide.

 

http://home.comcast.net/~SupportCD//OptimizeXP.html

 

I can't believe the amount of quality information there.