Surround Sound Vista

OK. I know this has been posted before but There's always one element missing.

Lets start from the top.

I am using:
MSI K9N2 SLI Platinum Motherboard (with optical SPDIF output) (sound chipset: Realtek ALC888)
I am running Windows Vista Ultimate x64 (soon to be Windows 7 Ultimate x64)
and I'm using an old JVC RX-6000V A/V receiver

What I am attempting to figure out is if I can get 5.1 channel surround sound from my PC to a stereo reciever. Same as the others.

Here is what I have found so far:

• If I play games or if I play mp3's my receiver will only receive, and enable 2.1 channels.
• My receiver cannot handle AC-3 Over digital
• If I perform a windows audio test* and test either "DTS Audio" or "Dolby Digital" my receiver will turn on all my speakers and I can hear audio out of all channels for the duration of the test
• The receiver will turn off the extra channels after the test is complete

*= Test found by: right-click on the sound icon (in system tray)-> select playback devices-> select Realtek Digital Output-> click
Supported Formats tab (The tests are under the encoded formats category)

I know the games I play can handle 5.1 surround sound, but from what I've seen my guess is that I need to spoof a DTS or Dolby Digital signal to my receiver. That is only a guess however. If anyone knows how to make it work I'd love to know.