Did the nVidia driver maybe overwrite a portion of DirectX v9c? Can you still use the Windows Control Panel "Display" and see if that matches the nVidia control?
I am not familiar enough with AA and AF to help much. I do know that I could mess things up bad with my old ATI card if I adjusted things, but I do not recall the old settings, but I do know that it did not have 4x4 AA...
