On Windows it has to be NVidia and 100% compatibility it has to be Quadro. Don't get me wrong the other Nvidia card will work but when you are kicking around hi poly meshes then Quadro is just smooth.
I have run both and current rig has a Quadro 4000 and hasn't missed a beat in 2 years.

On Mac OSX the ATI cards drivers are much, much better at running Maya for some reason.