I personnaly use Nvidia 6.50 driver in combination with Win2k SP2 plus DX8a. Rock stable with all my games, but I dont know for performance, maybe it's not the best combination.
It's better to be rich and healthy than poor and sick!
The 12.x drivers smoke those others for win2k. do a comparison on 3d mark and you will see for yourself.
I myself find the latest ones here.
http://www.the-ctrl-alt-del.com/
I know the 12.40's are there now.
Also www.reactorcritical.com has them.