Since I started using XP, I noticed that games performance was terrible. Idle CP load stayed at around 12% all the time. This lead to jerky graphics, choppy sound, every game I tried was the same, even DVD playback suffered. I tried the tweak
http://www.tweakxp.com/tweakxp/display.asp?id=822
but I didn't see any difference. If you also experience this problem and have a Zip drive, here's how I solved it.

1.Right click "My Computer"
2.Select "Manage"
3.Click on "Device Manager"
4.Double click on your Zip under "Disk Drives" ( it may be listed as "IMG VP01" or something similar - pick the one that's not a hard drive)
5.Disable the device

If you then need to use the Zip drive, simply re-enable it by following similar steps.

This worked fine for me, XP is now as fast as 98 (well, almost!).