So, I'm sitting here thinking about what to get for college and trying different configurations of macbooks and macbook pros to see what I'd like best and how much it'd cost. To go from 2 to 3 gigs of ram on the MBP 15" is $517. To go from 1 to 2 gigs on the MB is $157. Is that just a typo on apple's site (on the total cost thing, it really does jump up $517) or,if not, why the heck does 1 gig of ram cost $157 for a MB but like four times that for a MBP? What's different about the ram?