Every game should be capped at 60fps. Anything higher than that starts to look stupid because its way *too* smooth. Half-Life is capped at 60fps also, btw.
Actually, I would like to cap all my games at 15fps. Yes, you heard me right, 15fps. No, I am not being sarcastic. I think its because my mind gets the impression that the game's graphics must be uber awesome if my computer can only run it at 15fps; thus I think the graphics are better than they really are.