For using the Mac Pro to do things like 3D CAD/animations, which video card is better? The ATI Radeon HD 2600 XT 256MB which came with the standard system or the NVIDIA GeForce 8800 GT 512MB? Which card is compatible with Leopard, Windows Vista and Linux? I don't want to have driver problems. If you have suggestions on 3rd party products, please let us know. Thanks.