Other than the obvious differences [13" screen vs 15" screen], [1gig RAM vs 2gig RAM] what other differences are there between these two machines? Upgrading the RAM to 4gig on both machines from OWC is the same, so I don't count that as a problem. 95% of the time, the machine would be used as a desktop unit with an external Screen and keyboard, so the screen is not a "big" deal. My big concern is performance. Are the processors the same? Would these two machines benchmark out the same? What would I be compromising by getting the 13" machine? We are talking $800 diffence in price..... I don't mind paying for what I get... I'm just not sure what I'm getting other than a bigger Screen?