I don't suggest macs for university. I had to use one for some lab work and I hated it. not just me, most people were very upset about it. But I am in sciences, so I have no need for a lot of the art programs that macs are known for.So, Unless ur in an graphic art course. They have some great programs for that.
They can get viruses btw. I'm not sure why someone said they could not.
Not as many viruses, but if you are not stupid online and have a good anti virus, you will be fine with windows.
I know many people, mostly CS students that go mac and partition the mac to xp/linux/vista until they can go back to windows or linux.
Most programmers I know get a windows computer and just partition it to have the mac OS and linux OS.
You get all worlds that way, its great for creating videos.
Anyways,
just ask lots of questions.
Best of luck