Hi! I currently have the MBP 15" (Late 2008) with 2.8Ghz CPU. I have the 'Higher Performance' option turned on, meaning the GeForce 9600M GT is active, and the MBP runs in closed clamshell mode. Whenever I open a 1080p file (QuickTime MOV, like the ones that iMovie spits out), I have choppy playback. I tried quitting all other applications and made sure nothing else is using the CPU, but no dice. 1080p YouTube works perfect, but here's the catch: my previous MBP 13" (Mid 2010) had none of these problems with its integrated GeForce 320M and 2.4Ghz CPU. Both computers are Intel Core 2 Duo, and my current MBP by all means should outdo the 13" in every aspect, but 1080p playback is a b**ch. OS X Lion installed with latest updates and all, but this occurred in Snow Leopard, too. Tips? Ideas? Thanks!