I'm debating between an air and a mbpro. I'll mostly use this for internet, excel, and iphoto. Is 4gb going to be enough for these uses? I have an iMac with 8gb and it really screams. How much better is the screen on the mba? I played with both at the apple store and I didn't really notice a difference? I do like the air since it was just updated. I figure if the mbpro's came out with something really cool i could sell and wouldn't be out that much money.