I found a work around on the steam forum which says:
"I played it just fine. It uses DirectSound3D so if you want surround sound you'll have to use a program like Creative ALchemy if you have a Creative card or 3DSoundBack if you have a Realtek based audio codec. If that doesn't bother you then you can play the game without troubling yourself to do anything at all. "
While looking for that, I also found the solution for Far Cry 2:
quoted from the gamestop forums:
"I had this problem, too. I'm running Vista64 with an X-fi card. I had no surround, only stereo. I was able to fix it by editing an .ini.
Look in the "\Far Cry 2\Data_Win32\SoundBinary" folder and edit the DARE.INI file.
"DISABLE_OPTIMISATION=TRUE"
Change it to false. "
I found on another forum that someone said they just needed to enable "processing". I'm not sure what that means, but I don't have surround sound so can't test it.