It used to run at like half speed on my Athlon 2500+ but it runs nice and chipper on my E6600, so... anything around an Athlon64 3800 or higher? :)
I just got done playing some Demolition Man and Blade Force...ahh, good times. This new release is flat out fantastic. I was a bit bummed when I realized that I needed ASPI installed to use the emulator before (I probably had it left over from something else on my previous box), so I hadn't really gotten a chance to play around with it on the new machine until now, and gosh darn was it fun.