Here are a few comments for the OP, coming from a dual emphasis graphic design/illustration student about to enter his senior year:
-by this time, most people in all of my design classes have laptops, which are VERY nice for working on projects during classes that aren't help in computer labs and doing research as the teacher is lecturing (googling a typeface they mention that you aren't familiar with, for example)
-on the other hand, if you will be working with RAW images, a Macbook wouldn't be great because of the intergrated graphics (I have Aperture on my Dualie G5 that has 3.5 gigs of RAM and the workflow is smooth...some of my fellow students have tried using it on their Macbooks, however, and found them a bit lacking in that department)
-something that I've found to be a nice middle-ground solution is to have a powerhouse desktop at home and carry around a 2.5" portable harddrive (mine is a 40 gig laptop drive I put in a case, which can be bought for around $75 put together, or closer to $40-50 if you buy the drive and case separately. Look around at sites like
www.dealnews.com to find good deals on such things)
-someone above also mentioned that the price would be significantly lower if you upgrade the computer yourself. DO THIS. From what I've seen, the Macbook is ridiculously easy to upgrade, and I would imagine the new iMacs have similar upgradability.
I hope this helped. Whichever route you take, enjoy your new computer and take everything you can from school!
-Colin
