Drivers for Mac Pro 2

I have a Mac Pro 2, and I want to put the best CUDA-enabled nVidia card I can in it. An obvious choice seems to be the Quadro 4000 for Mac, but when I look at the available drivers, the release notes say

> This driver update is for Mac Pro 5,1 (2010), Mac Pro 4,1 (2009) and Mac Pro 3,1 (2008) users only.

Uh-oh–should I not assume then that this card will work (with this driver) in my Mac? I didn’t see how to download older drivers, and the same notice is in the notes for the 8800GT. Does anybody know a card I can use?