Try to find Resident Evil 1 (PC Version).
The soundfiles are *.wav I think.
Zombie moaning, shots, screaming and more.
I don't like real songs that much for use as background music. Ok, if the players enter a disco or club / action scene then it's alright. But the other time I usually use some noise or instrumental music.

Lustmord
SPK
Merzbow
Wumpscut
Masonna
Mike Patton

and stuff like that is great.

KMFDM (you guys can enjoy the north american tour ^^)
Combichrist
and some metal or hardcore bands cover the action scenes.