LinuxCNC would be the natural choice, then. It can be a bit finicky with PC hardware as, unlike Mach, it uses a realtime kernel for smoother control. Best thing to do is run the Live CD (no need to install) and run the Jitter test to see where your PC stands. Wifi cards and on-board graphics seem to be the worst culprits for poor response times. If you have neither of those, then you'll probably be good to go "straight out of the box".