Fellows, I purchased 13" MBP last thursday, so far I'm not 100% satisfied with it due to the fact that I have been eyeing on 15" old MBP. i have been considering taking this one back and get old 15" MBP. I use the computer mainly for Excel spreadsheets/word...few photoshops and so on. The one thing that makes me to hesitate is the fact that the old MBP's ram slot is only expandable up to 4G. so Im not totally sure paying extra $140 for the old 15"MBP is a rational decision. some help?