I can build a killer ass gaming computer for less than $800.
Currently:
Acer X233Hbid 23" monitor
CoolerMaster HAF 932 Case
Intel Core2Quad Q9400 2.66GHz (OCed to 3.2 on air cooling, ~50C-55C with Prime95 running for 28 hours)
Biostar TPower I-45 MoBo
GeForce 9800GTX+
4GB OCZ Reaper HPC DDR2 1066
500GB HD (nothing special here, just highest rated, with a good price)
Cheap DVD/CD burner
Built it about 9 months ago for ~$1100 total, including monitor. Its nothing too special, but it runs Fallout 3 on Ultra settings at about 30-40FPS