30fps and above is usually considered the mark were games go from crap to very playable, anything above 60fps usually wont matter due to your monitors refresh rate.
25fps and below is kinda unbearable to play, 25-30 is OK, but 30 is the holy grail
if ur comp can run crysis on max settings in dx10 at your monitors native resolution, and its above 30fps, ur doing amazing stuff.