I have a Mac Pro with what seems to be a dying 8800GT. I have seen one instance so far of a green followed by grey flickering screen with lots of artifacts. A hard reset solved the problem and I am now using the computer. However, my reading of these forums would suggest the 8800GT is on borrowed time. The Mac Pro is only a few months outside of Apple Care warranty (typical). Is the PC version of a 6870 - specifically this one; MSI HD 6870 Twin Frozr II 1GB a viable alternative? Reading around would suggest that this should work without Firmware modification, and, under Lion, I shouldn't even have to install drivers.