vista sound problem

I'm presuming you are referring to the audio settings on the control panel - where you can set quality and type, yah?? You've set them to full up, etc etc etc... correct??

If I'm not mistaken - and I may be since I didn't play with it much - Apps like VLC and WMP don't convert stereo sound to 5.1/7.1. Rather they decode and pass along whatever the source is. So if it's a stereo recording, you get stereo. Your game has multi-channel sound, and provides it's own output as well. So that's what comes out of the speakers.

On my own setup, I use the optical output from my soundcard into a (NAD T754) receiver, which has it's own D/A converter. I had played with the software that came with my card (Auzentech Prelude), but the hardware based decoding was clearly and immediately superior enough that, once I plugged in the digital output to the receiver, I never even thought about going back. After noting a recent driver update that added DTS support, I went and cleaned the audio apps that came with the card off of my comp entirely and just installed the new driver.

Have you downloaded the latest drivers for your sound/motherboard?

Also, maybe get a decent sound card to replace the onboard sound, and then get the latest drivers from the manufacturer of the sound card. That'd probably solve the problems. I just picked up a Sound Blaster Audigy SE for $15 on clearance for my ASUS board. Sounds cleaner. Has 5.1, 7.1, and headphone modes. I like the included utility; it has a lot of tweaks and settings to play with. But, who knows, your onboard audio may be just as good as an Audigy SE card.