I am experienceing the problem some are having lanching AE CS6 with ATI graphics cards so though I would look into changing to a Nvida one. Whitch ones work well with AE on macpro1,1 (2008). I am a student so will probably but used.
PS would be good if it worked with FCPx/Resolve.
Any graphics card which supports OpenGL 2.0–capable , or more.
Hope it Helps
PS the more the better
I got a GTX285 for a good price .. on eBay. I have other issues .. but I believe that the graphics card works fine with the latest update.