There are two important criteria for any computer purchase.
A. Can you get the work done on it that you need to get done?
B. Can you get help for it if you need it?
Unless you need Windows-specific software, criterion A is really about power, performance, and screen real estate. Pick the fastest computer with the biggest screen that you can afford.
Criterion B is the most important. What does the helpdesk at your college recommend? What’s used most widely in your field? If your computer breaks, where will you go to get it fixed? Apple support is head and shoulders above most PC manufacturers’ support, but a lot of colleges have helpdesks, so it’s good to see what they use.
In the absence of any software requirements (like, say, AutoCad) that would require Windows, and in the absence of any extra support from your college’s IT department, I’d recommend getting a MacBook, because they fulfill both criteria with less hassle. On the other hand, if you have a good friend who’ll do Windows support for you, or if your college has good Windows support, you’d probably do well with a Windows computer.