Look into what the courses you intend to take. If you're taking a computer science or computer engineering program, you're likely to be using languages that have plenty of tools available on OS X (though you'll probably need to SSH to the school's linux systems to test, since that's where your TAs and profs will do the grading). If you're planning on getting an MIS degree, etc. this is more likely to do things like VBA for scripting MS Office, Visual Basic .NET, etc. that is going to be easier on windows.
It may be awkward if the professor or TAs are using windows and you're using OS X, but if they're using linux or other UNIX-alike it shouldn't be an issue. Also, i doubt you're going to be the only one with a mac, so you should have some support from peers. Again, though, if you're in an actual CS/CE program, OS X should be just fine, it's only when you get into the MIS stuff that you might run into trouble.
-Lee
EDIT: You also mentioned "I.T.". For IT i'd say you need to be running the same platform your users are on. It's not strictly necessary, but if you're admin'ing a bunch of windows machines, but you don't use windows, that doesn't instill a lot of confidence in your users. You can certainly virtualize, used remote desktop, etc. to successfully admin windows from OS X, but it definitely seems to be "fighting the flow". If you're admin'ing UNIX-alikes, OS X will be fine. If you're admin'ing macs, obviously OS X is the right choice.
EDIT 2: If you are going to be involved in a business, or even academic setting where Windows is the primary platform in use, you'll need to take a more mature attitude about it. You won't get far calling it Winblows, etc. You may dislike it, but if you choose education or a career where you're exposed to it, you're going to have to deal with it professionally.
