It really comes down to what you need, program wise. If you have to use a Mac specific program for your major, then it really isn't a choice.
Beyond that, for me at least, PCs are the way to go. The price differences between the two are outrageous sometimes and build quality isn't that huge of an issue, depending on your PC brand. I've had an Asus laptop that I've carried around everyday for something like 3-4 years and never had an issue. I paid something like $750 for it and to get a Mac that was as powerful as it at the time would've cost me almost $2k.
As for virus vulnerability, i use a combination of three programs (Malwarebytes, Avira, Spybot) and have never had an issue on my home desktop. And trust me, I'm a huge down loader of torrents from piratebay and the like.
At the end of the day, its up to you. Do your homework and research so you can make the best educated decision based on your specific needs.