The first thing you should do is find out from your school what, if any, features or specifications they require your camera to have.
You'll want a DSLR, not a point-and-shoot. As for manufacturers, I'd stick with the big two, Canon and Nikon, not because their cameras are any better than those of other companies, but because they are the most widely used by professionals and advanced amateurs. As a result, there are more sources of support and accessories for Canon and Nikon cameras. You will probably find more professionals shooting with Canon than Nikon, but that's only because Canon got serious about the pro DSLR market faster than Nikon did. As a result, when pros started switched from film to digital, they didn't have much choice but to switch from Nikon (which was the KING in the days of film) to Canon systems. After they had invested thousands, or in many cases tens of thousands (or more) in professional Canon lenses, it didn't make sense to switch back to Nikon, when Nikon finally got serious about their professional DSLRs. For years now Canon and Nikon have been neck-and-neck. If anyone tries to tell you that one company is better than the other, stop taking advice from that person immediately. The truth is that someone just getting started can't go wrong with either company. You'll get equally good images from both companies. Just keep in mind that whatever company you choose, you're not just picking a camera -- you're investing in a system. After you've invested in camera bodies, lenses, flashes, and accesories for one manufacturers, you'll likely stick with that manufacture rather than replace all of those things when the other company comes out with its top-of-the-line product. I've used Canon and Nikon. Right now I'm primarily using Nikon, loving my D300 and (still) my D50, considering a D700.
Your first camera body shouldn't be a high-end one. Camera bodies are disposable. You're not likely to keep them more than a few years. A high-end body isn't likely to get you better pictures than a "prosumer" DSLR. High-end bodies have a few functions and features that matter most to professionals making a living with their photography, really giving their cameras a pounding day-in and day-out. If you were to go straight for the high-end camera, not only are you likely to frustrate yourself because it's so advanced, but by the time you're a working professional and can really appreciate all the features, that body will be a couple generations old. So, I recommend that you get either an entry-level or mid-level DSLR, like the Nikon D40x, D60, or D80 or any of the Canon Rebels, D30, or D40. You'll notice that I didn't include the latest cameras at this level (Nikon D90 and Canon 50D). That's because the previous models are still excellent, and will likely have price drops because of the new releases. You can get the above cameras new for prices in the $400s to under $1000. I recommend the middle of this range. Use the rest of your $2000 budget for good lenses, memory cards, batteries, flashes, tripod, bag, computer, software, and other accessories. Keep saving up money, ask for cash for birthdays etc., because the price of top quality lenses can be in the $1000-$2000 range.
.
