I've been playing with a consumer PC I've had for a few years. I've gradually updated parts of it manually, and since I don't play anymore, its specs aren't classified.
AMD Athlon 64 FX 3800 (~2.4GHz single-core)
1 GB crucial memory
250 GB 7200rpm HDD
ATi Radeon 4650 x512
22" widescreen HD monitor
Noise-cancelling headphones
And I kicked ass on that thing. Wheeee
I've had linux and windows OS's on it. Trem always ran better under linux, once all dependencies were sorted out. I finished on windows, since, being a gamer, linux was a bad choice for that purpose.