A laptop computer can be useful in the classroom for taking notes, etc. Many colleges now have wireless networks, so you can be online from just about anywhere. The big problem at campuses today are viruses, trojans and worms. Whatever you decide on, the operating system that you put on the machine may be the important decision. If you are using Microsoft products, be sure to go with XP Professional. XP Home is not secure enough in this environment.
Some collages will require you to buy their security package before you will be allowed to connect to their network (cost can be minimal; maybe even free). A friend of mine is sending their son to a college that requires students, if they bring a laptop, to get it from Dell.
All of this is because of security issues. I would advise you find out from the collage just what they recommend before you spend any money on any system.
Regards,
Jay