Okay, people have listed reasons for both based on usability.
However there is something else you need to think about. Where are you going to college? Where are you going to live?
Is it an hours drive from your current residence, or is it a 6 hour plane trip? Are you going to be living in a dormitory 8 floors up, or are you going to be living in an apartment? What kind of major are you taking? Is it something where you will need a computer with you in class at times, or is it something where conventional notes and listening will be fine until you get back to your room?
Laptops are good for mobility and low weight - but they are bad because they are expensive, not as powerful as a desktop can be, and have power issues. Also, laptops are difficult to upgrade/expand.
Desktops are good because they are powerful, dont deal with those power issues, and can possibly be easier to use (depending on the user's preference really), and are relatively cheap - however they are bad because they can be heavy (monitor, tower, peripherals, etc) and there is a lack of mobility.
Personally, I live about a 50 minute drive from my parent's home. So I decided to build myself a desktop and take it with me. However I know I am going to be living in this residence until next December.