Hi guys. Mac newbie here, and I have a question about the GPU for the new iMac. I ordered my very first 27 inch iMac the morning they came out (which was very exciting. ). I kept it stock with the i5, 1TB HDD and the 675MX graphics card. I sort of regret not being able to upgrade (at the time) to the 680MX, and maybe to the i7, but I figured 3.2 ghz is still pretty good. I was wondering if after I received my iMac if I would be able to separately purchase the graphics card (I know it's a little bit more pricey that way) and install it myself and have a friend help me swap the cards, or if it would just be easier to change my order to have my iMac with the 680MX, although that would probably mean waiting until January. I desperately need the computer as soon as I can get it, though, which could be anywhere between the 24th and the 31st at least according to my order. I was also wondering if the 675MX is a good card, or if after awhile it will start to feel 'old'. Any ideas? Thanks for any and all future responses.