i spent under 1,000 on my rig.

AMD phenom quad core ( 4cpus) 2.8 overclocked to 3.2
GPU Radion HD5750 i have all my settings on high , highest , or 8 ( the difference between 8 and 9 isent noticeable really)
Most the higher end options are for 3D settings witch the HD5750 is 3D ready and my 32inch Vizio is also 3D ready but meh..

I got the PC from best buy for like 700~750 with tax and the HD5750 GPU was 120 , you can get the new HD6850 for like 150 i think but really not needed.