Hi all. I am considering a 2011 27" iMac for CS5.5, but CS5.5 (specifically Premiere Pro) require, ideally, an Nvidia GPU for the "Mercury Playback Engine", which uses Nvidia "CUDA" cores. How does the iMac, with the ATI card, run CS5.5 optimally - does it run smoothly, even without Nvidia? I am asking specifically about Premiere Pro & After Effects. Thanks - informed replies only please.