Still only played the demo (the full version waiting for me when I get home from work today...)
My spec:
Intel E8400 core 2 dual ~3Ghz
4GB Ram
ATI HD4870
Win XP SP3
Funny thing though, I did run the demo with the "first" start option (not the dx9 option) and it worked? As I understand it, DX10-11 isn't available for WinXP, I know there's some 3rd party DX10 ports for winXP but I only have dx9c installed (double checked with dxdiag). Anyone know how this is possible?
The only issue I had was that my graphic card started to get hot (I have a warning set to flash when it passes 60 deg celsius, but only after about an hour of gameplay.
Performance wise I didn't note anything special, it run smoothly, graphics looking good etc. I guess I will see the true performance when running the full version on a larger map than what the demo allows.