Mine is just an upgraded Dell Optiplex 745, the CPU, mobo and cooling are all stock. It manages to play everything I throw at it.
CPU: Core2Duo E4300 1.8ghz
RAM: 4gb PNY in dual channel
HD: Seagate 750gb, Seagate 2TB
PSU: Thermaltake 600 watt
GPU: Gigabyte GTX 550 Ti 1gb
OS: Win 7 64-bit
Audio: Video card via HDMI into my TV then out to my soundbar via toslink.
It's not super amazing but it still blows my PS3 and 360 away.
I don't run.
And if you ever see me running,
You should run too.
Because something is probably chasing me.