What's the song the guys sing in MEN SUDDENLY IN BLACK?

Just watched this the other night, and there's a scene where the four guys are driving in their taxi and singing a very heroic-sounding Chinese song (I think it's after they visit Tony Leung Ka-fai's character), sort of reminiscent of A Laugh to the Sea, but I don't think that's it. There's also a tranced-up version of it in the closing credits. I'm absolutely certain I've heard this song before in other films, but I can't place it. Anyone know the name of the piece, as well as who might be singing it over the closing credits?