Just speaking from experience. My first time around I went with ibuypower and got a $900 machine. I really regret it. Since I didn't really look into it, I ended up with a mobo using an unpopular socket type, making a CPU upgrade impossible, PSU was a weak off name brand that died just past the warranty date and the case was meh. I used $600 to replace everything but the case and RAM, which I later did replace the case, it would have added another 45 to that cost. The PC I was able to build with 300 less dollars was 10 times better. To actually put it together is maybe an hour and a half if you've not done it before and have never seen the inside of the computer.
If you want to buy a prebuild, I believe you have the answers you were looking for in other posts. But I really believe it would behoove you, especially if you plan to go to school for it, to build it yourself. And lots of us here have the knowledge and experience to help anywhere you may get stuck.
I'll also add that any prebuilt running in the 500 range is aready a few years out of date, and with a new breed of graphics cards and CPUs coming out, the likely hood of you being able to game with a respectable, or even tolerable frame rate and resolution for more than the rest of the year is very slim.