5.1 surround in Vista

I'm trying to get my PC to work with my 5.1 surround receiver.

I'm using an optical out through the digital port on the sound card( Creative Sound Blaster Audigy SE 5.1 ).

It's throwing me because it works in the config menu when I test the Dolby and DTS sound settings. I get sound from all five speakers and the woofer during the tests, but when I set speaker configuration in the sound manager to 5.1, from 2, I only get sound from the front left and right speakers; The rest of the speakers do not respond.

I can't get 5.1 sound out of any of any games that I've tried nor does it play music from those speakers.

If you guys could help me out with this I'd appreciate it.