Before you shell out the money for a Mac, perhaps find out which platform you'll be using in school.
The Apple for graphics mindset is antiquated.. this hasn't been true for many, many years. If you're in need of quality graphics then you have to start with which graphics card you need..make sure it's not on-board and do you need 256mb or 512mb?
Next is RAM.. imo, the more the merrier applies here.. but there is overkill.. anything above 4GB is probably more than anyone will need unless you're getting into video and 3D animation.. if that's the case, then a Mac is probably the way to go.. but not a laptop. Also check out the pros and cons of DDR2 vs. DDR3.
Talk to your profs.. find out what they recommend as far as specs go and then start comparison shopping.