AlecStaar,
Yes, i have a windows 2000 computer here too, and it does none of the constant I/O reading/writing.
It is simple idle if you dont use it. And that i believe gives you really 100% of the available CPU when you need it, hence i think Windows 2000 ought to be faster than XP.
I even did (to be sure) clean installs of Windows 2000 AND Windows XP today! Same results again. Windows 2000 no activity at all and Windows XP - whatever i do it keeps on behaving like this. Isn't it odd, that windows XP needs to load and write from the harddrive all the time?
If you're using Windows XP yourself put your head next to your computer and just sit there idle for a few second and listen. You will hear the harddrives writing even if you have nothing runing at all.
I have tried to localize exactly what it's doing. I even probed the Nic to see if it was sending out commands to M$ homebase or something but, guess what? It wasn't! lol..

I tried to disable all the services that i could under XP but i still cant get it to stop writing to the harddrive. Why do you need a power manager for XP when you only have one harddrive? It wont ever be able to go down anyways! It always loads!
:x