You should definitely take it. Take the precautions you stated about locking it to the desk, but having a computer at a university is a must now.
Pretty much all universities have computer stations or areas where you can go and get stuff done on their computers, however it isn't always easy to access them. They could be full, it might be closed, or the weather could just be horrible.
If you have to, you could even go and get a cheap netbook for taking notes in class if you need to do that. I don't really use desktops anymore but I have been using a netbook for 2 years in replace of one; just recently upgrading to a MacBook saves me a LOT of time and effort.