I'm going to be waiting for the next refresh of iMacs, whether it is a month or 3, but I was curious is there a huge difference between these graphics cards? Say I wanted to game on the computer. Not hardcore gaming, maybe like Battlefield the most recent one. That should run fine, right? Also would I be able to upgrade later or no? I will also be upgrading the RAM but I believe it's cheaper to do so with a third party, correct?