howdy,
i have at home a dual core opteron 175 (2.2Ghz clock/1MB cache per core) 2GB ram, WD 73GB raptor HD, & a single 7800GT (PCIe/256MB ram) video card, onboard sound.
i was able to run the demo with max settings just fine, looked very nice, and was smooth. while up in the air i was able to move my point of view around without any noticable lagging effects.
hope that helps.