I'm tired of the low end GPUs in the MacBook Pros and iMacs, want to game but don't want a PC. I'm considering picking up a second hand Mac Pro and upgrading the GPU - however, I know there aren't currently drivers available for eg. the HD 5000 series. What would happen if I were to install one in a Mac Pro? Would I get no image at all in OS X? Would I get unusable video/flash/photoshop performance in OS X? Or would it function fine for non 3D applications?