This probably belongs in "tweaking" forum, but I thought more of you would see it here.
Follow the link to find two in-depth documents on how to tweak your system for best performance. Both are XP specific, but many items can be implimented in other OS's.
http://www.tweaktown.com/document.php?dType=review&dId=324&dPage=1
http://www.tweaktown.com/document.php?dType=review&dId=434&dPage=1
Enjoy! ;D