Learning Mountain Lion is possible on 2006 Mac Pro 1,1, but not with my stock Nvidia 7300GT. The ATI HD5770 is a supported card upgrade for my model. Also seeing lots of Nvidia 8800GT for sale. Which is a better graphics card to update to? Are they more or less the same thing, or am I correct in assuming ATI model might be better option for better performance w/ Lion, and attempt to get Mtn Lion running? Thanks in advance.