Source : AppleThe ATI card was offered as an option then, but removed shortly later. This option has resurfaced again on The Apple Store (Singapore).
Generally, ATI has historically provided better performance (espcially for 'pro apps') over similarly powered NVIDIA cards. Barefeats has recently shown so too. The results are somewhat puzzling, but true. Be it ATI, NVIDIA or even Intel, we can only hope fervently that cohesive collaborations between themselves and Apple --- such will bring about optimized performances for us, mac users.
p.s. Interestingly, the NVIDIA Ge