I'm about to pull the trigger on a G5 Quad. I'm new to Macs, so I'm a bit hazy about the compatibility of video card options. The card I'm interested in is the Nvidia 7800GT, but I don't want to wait 8 weeks for the system to ship. Questions: 1) Is there a Mac-only version of the 7800GT, or is the PC version interchangeable? 2) If they are not interchangeable, will I be able to buy any 7800GT in the future or will I have to buy it directly from Apple? 3) What about the ATI X800XL? Will the PC-version work in a Mac, or is there a Mac only version? 4) For a dual 30" cinema displays, would I need two 7800GTs? How would dual 7800GTs compare to the Quadro 4500? I'm guessing, no SLI support on Macs.