UPDATE: What about RAM? 4Gb or 8Gb? How much real difference is there? Hi, They're finally out!! I'm gonna get my first iMac and I need your help understanding which one fits better my needs. Basically, my budget lets me choose within a 21.5" with a 2.8 i7 processor or a 27" with a 2.7 i5 processor. I prefer the computer to have more power than screen real estate, but I just don't know how much a difference there is between an i5 and an i7 and if that difference is worth the smaller screen size. Thanks for your help!