I was getting ready to buy the Dell 2408 WFP when I noticed the 2709. Looks great but one reviewer stated he put two ATI Radeon Hd 4870 graphics card in it. My question is this: In going to the 2709 rather than the 2408, will I be sorry, i.e., will I need two cards to make this work properly? or is there really no difference between a 24" and 27" when it comes to the graphic (video) card? Thanks for any help. This will be used with a mac pro.