While Macs are certainly great machines, you can get a PC laptop with the same or better specs for much cheaper! I personally recommend Lenovo - I got a laptop from them two years ago (mostly for gaming, but obviously can be used for school/work purposes as well) for about $800 and I LOVE it. Lenovos have a reputation for durability, which is a definite plus for me. They have a neat tool that might give you an idea of what kind of laptop you could get within your budget:
http://shop.lenovo.com/us/en/landingpage/laptop-finder/
I'm considering getting one of their Yoga convertible tablets (the kind with attached keyboard that you can flip around in a bunch of configurations) for portability/convenience of taking notes in classes etc, although I don't know that I'd recommend one as a primary computer because of the smaller hard drive. Anyway, that's my case for Lenovo/PC laptops, hope it's helpful!