Anyway, in that price range, you should be able to do decently.
I'm not too great with brands, and a quick search didn't have anyone I really felt comfortable with recommending. So, instead I'll just outline what you should look for in that price range:
3.0Hz+ CPU (AMD tends to have the most bang for your buck, saw a few i3s and i5s, though.) (Not sure if this is still relevant, but cores used to not be able
8 Gigs of RAM if fairly standard, and frankly all you need.
GTX 6-series (660 most likely) or Radeon 6-700 series. (I prefer Nvidia but whatevs.)
You'll want at minimum a 500W power supply, the higher the more stable.
Thats pretty much all that counts, Gaming wise.
A few tips:
DONT get suckered in by a Blue-Ray drive. You wont use it, and they're expensive.
Try to get Windows 7. It tends to be cheaper and its better.
Fancy cases may look good, but tend to hike the price. You want airflow, not lights.
Be careful with pre-clocked rigs. They get more power for less, but a bad clock can make it unstable.
Thats about as much as I have to say, so yeah.
Oh, and here's a few good sites:
http://www.newegg.com/ <-my personal preference
http://www.tigerdirect.com/ <- Heard good things about here as well