The final solution looks like this:
I ran into an interesting problem with my Mac Pro. I am using it as the platform for my dissertation research in 3D and am triple booting into OSX, Windows, and Linux. Because my research is graphics intesnsive, I wanted to upgrade my graphics card. I was also looking for an excuse to get a better card for gaming in Windows than the official Apple/ATI 570/580 cards Apple currently offers for the current generation of Mac Pros.