There is quick moment in the beggining of the movie where Shaun enters a bus and sits down and the sound track cuts in with about 3 to 4 seconds of the track i'm trying to identify. It is prior Shaun's realization that the dead have come back to life.

sorry i dotn' have a better source for it, The only else i've heared the track is in a nightclub they play down here. If anybody know's the name i'de appreciate it.