Ay, i gotta agree with Ghost and dude above me on Bruce tho. That dude was a very qualified martial artist. And he was in amazing shape. The best shape you could be. Practically no fat, all muscle. Perfectly honed moves and techniques. Now, whether he'd have the "killer instinct" that, say, a professional boxing veteran would have, i dunno.
But Bruce Lee was not a bloke to be taken lightly on the fighting front. He'd prolly whip the fuck out of a big, heavy, slow musclemountain. I mean, i agree that in the general public, the effect of (asian) martial arts is often overestimated. You have people who took 20 classes and think they're the man. Not so, of course, but a seasoned kung fu artist for example, with his skills honed to increbile levels, is bascially a fucking war machine.