Black Viper
His Win2000 services guide is a must read. Services are programs which run in the background, slowing the pc down. Most of these are not needed. He explains which ones you should disable to optimize your PC.
Michael's Win2OOO guide
Here you'll find a great set of tweaks for Win2000.
Axcel216
It's a very good site to find information on tweaking windows.
There is also a zip file available for download which contains all the text from the site in textfiles,
regfiles,... very handy to find a tweak without need of internet.
XPlite
XPlite gives you the power to set up your windows machine the way you want. The power to remove unwanted features, the power to remove upgrades that go bad, the power to strip potential security and privacy threats out by the roots.
run on old computer
Guide to tweak win2000 to run on an old computer.