I'm a student and I fine the 13" is more than perfect. Unless you will be doing some kind of design, dont get the 15" or the 17".
The 13" screen is big enough and it's uber transportable. It fits in my dakine backpack with the laptop sleeve perfect and when I'm taking notes in class, it fits perfect on the desk.
Oh, and I got the 250gb HD with the 4gigs of RAM MBP and it came to 1799 because I'm a student. I also got their 3 year warranty which was $181 and since I had a buttload of music on my PC I bought the one-to-one to have apple do all the transfer of files and with the one-to-one you can go and do tutorial sessions with a mac guru at the apple store.
Best purchase ever. I don't know how I lived with PC all these years.