I use an IBM ThinkPad. The only requirement for university was Windows XP or 2000, and in December the Apple line hadn't switched to Intel. Sadly, I have been craving a Mac since, they now run Windows, and I haven't touched .NET since I bought it.
What I'm saying is that if you study Web Development (as I am) or Computer Science you will probably end up having to work with Microsoft .NET (We have a hundred iMacs and eMacs on the next floor, but we use Pentium 4's...) but now you can pick up a MacBook, install Linux and Windows, and you wont have any problems.