You should be able to put together a decent rig on cyberpower for $1000.
Here's on for $913 excluding shipping http://www.cyberpowerpc.com/saved/1EMUJH
gtx 660 ti
1TB 7200 RPM
Free Borderlands 2
You would probably be able to move up to z77 and a 3570K on that config and still be under $1000
Cyberpower has gtx 660 Ti for $190 this weekend, so that's a great deal you should jump on. This rig would play any of those games on ultra at 1080p.