I'm trying to decide which MBP model I should get. I was going to get the 13" with 8 GB RAM, but I also kind of like the 15". If I got the 15", though, it would be with only 4 GB RAM. Speed is definitely important, I'm ready to get rid of my 256 MB RAM iMac for sure. Which should I get? I want to get it soon and want it to be really fast (13"), but I also kind of want a bigger screen (15") Anyone else thinking the same? THX.