I will tell you this now. I am PC biased as I have always had problems using a mac and am more knowledgeable on a PC's workings.
There are two major things you should consider when choosing a computer. What do you plan to do with it, and how much are you willing to spend?
When it comes to deciding based on what you want to do with your computer, the difference between Macs and PCs is slowly shrinking, but there is still a gap. People who lean more towards programming and gaming tend to choose PCs. More and more games have been adapted for Macintosh use, but they sometimes they come out considerably later than the original PC release date, if at all. Also, a majority of programming is done in Windows or Linux (The later being the system we use at my school), so science type people tend to lean towards PCs. On the other hand, Macintosh is made with the artist in mind. If you wish to work in artistic media, making the art for games or movies than a Macintosh would do a better job. The art department is full of apples.
As a student, you may want to check what types of computers your school uses. I found that trying to get files to work between the two is too tedious for me to bother with when it's Mac and PC. Once again while the compatibility gap is shrinking, it still tends to creep up at the worse possible moments.
The biggest thing you should consider though is how much you are willing to spend. Macs tend to be a tad expensive... most run an average of $1000 for a new quality laptop. PCs tend to be cheaper, but you have to be careful with them. They're a bit finicky and don't like to be manhandled. :) I've broken my fair share by leaving them to jostle around in my backpack.
Then of course, if you do narrow it down to one or the other, you must decide what kind of computer to buy of that type.
I would recommend a simple net book PC for a computer. It's good for school and simple things and inexpensive, so you get one faster. Nice and small. Granted... it is no gaming system, DVD player or CD player, but it will get you through your studies. :)
There are some sites listed below that might help.
Good luck!