I find it quite portable for its size. I carry my 17" MBP, mouse, power brick w/grounded extension, and my books/notebooks in my backpack almost everyday. Yes, the 17" is kinda large for the flip desks, but I just use it on my lap when I need to in lecture.
That being said, only get the pro if you need the pro (more power, dedicated graphics, etc.). If you are only going to be using it for documents, iTunes, and web, get the MB and a nice monitor for your dorm if you want a larger screen.