Okay I did a quick build for you. It costs slightly less than 600 (without shipping) and does not include a monitor. However, it will easily play most games 1080p probably on high. It doesn't include windows, but since you're in college you can probably get a copy for free or at a greatly reduced price.
For $ 423 this "run" games at decent resolution level as 1680x1050 and mid mid level of graphic detail.
So with that you can get a good build, and enough space of some upgrading. The bad side of the story is that because the socket, you wont have many processor to choice for upgrade. But well, I can say that with this you can play while you save for a HD7770 and get better performance.
Well thats even better, an intel build is the way to go. In my build i didnt included a HDD, which is at least 80 bucks more. So my build would be going 500 bucks.
I guess that going cheaper in memory ram, changing 8GB for 4GB and take the saved money to get an 6790 would help, since he is not going to use more than 4GB in games. The better memory interface will help at higher resolutions, something like this one.