For school, I honestly suggest a netbook over a standard laptop. Any decent school is going to provide you better hardware to do graphics work on than what you can afford to get in a laptop. Plus, the reduced ability to play some of your favorite games is going to keep you more focused on your lectures.

Trust me, it makes a difference. Plus netbooks are light and easy to carry along side the massive textbooks you tend to lug around as compared to even a 15 inch.