i had the same decision you have, and i went with the 15inch, due to the extra ports, pc card slot, and firewire 800 (for video editing) and also the fact that the 15 isnt that much bigger than the 12 anyhow. dont buy ram from apple, they charge WAY to much, i got 2 gigs of ram for about 220$ total, where apple wanted like 850$ for 2 gig's... also the dvi port on the 15 is a full size dvi port. and the 15 inch comes with a better lcd, than the 12..