Buying my first iMac to replace an aging PC. I will installing Adobe Design Premium at first followed by either VMWare or Parallel for windows and Windows XP or 7 later for my CAD/CAM programs (I have a newer laptop to run these programs for the moment). I'm going with the 27" 3.4 I7 with either the 6970M 1gb or 6970M 2gb. I would like to upgrade the memory to 16gb but the extra $600.00 seems a little high considering the current retail price of memory from Crucial and others. If I make the upgrade myself does it void the warranty. Swapping the memory looks like a piece of cake on the iMac.