I'm not sure why. I guess I'm a glutton for punishment. I haven't played anything or won't for awhile that takes advantage of these drivers and DX9. Heck I think It's probably pointless with my GForce 4 TI4400, I don't think it supports dx9. I think you need an FX card or better. I don't know. Anybody? Thief II is the only game I've played and it had no problems, then again this game is what 2 years old.
NV 43.45, DX9 and WinXP pro - stabile no problems at all.