I have an old 8800GTS 640MB and have been having nothing but problems with many Nvidia driver releases. Crashes in Vista have gone from fairly common to rare occurrence in Vista thankfully. But they still happen. I had to wait... over a year for things to be comfortably stable?
The Windows 7 Drivers seem to do well enough for the desktop, but fall short in popular games:
Fallout 3 crashes in the outside world.
WaW crashes.
COD4 works occasionally until it randomly encounters a corruption issue where the screen is garbled beyond recognition. Only remedy is a system restart to get a usable game. Sometimes objects and walls randomly disappear.
Haven't tested Mass Effect yet, but I don't expect much better.
Meanwhile my friends who have ATI cards report games work fine in Windows 7 and observe that they've experienced few if any graphics related crashes in their system's lifetime.
Nvidia always makes technically superior hardware to ATI, but at least over the past two years I've had with Nvidia their drivers are not comparable. The Vista crash data seems to corroborate this, otherwise I would guess it is merely my particular card.
As it stands, Nvidia is losing on two fronts and only winning on one.
Price/Performance: ATI
Driver Quality: ATI
Performance: Nvidia
Pricing is a different arena than this issue, but nonetheless it gives ATI further overall advantage. I don't care if I can get a higher FPS if the game crashes. Along with their refusal to implement DirectX 10.1 (Why?) I find myself fed up with them. I hope for their sake the Ion platform is a huge success in the burgeoning netbook market because I can only see ATI doing better in the desktop market.