In nem anderem forum hab ich das gefunden, der hatte das selbe problem..
YESSSSSSS!!!!!!!!!!!

This fixed it.

!) Download this:
http://files.filefront.com/Alchemy+U.../fileinfo.html
(You don't need a Creative card)

2) Install

3)Add game
Game Path: Path to game in steamapps
Install to subfolder Binaries

4) Vista compatibility mode
Right click on program in Binaries, compatibility tab, Run game as if in Vista

5) SOUND NOW WORKS IN CINEMATICS!!!!!