Windows 7 and speaker setup

Hi

Not sure if I am going to be able to explain myself properly, but here goes.

I have my media centre, which is running Windows 7 and has the latest audio and video codecs installed. The media centre is running Eden with the built in DSplayer and is connected to a Yamaha receiver through HDMI.

I was struggling to get anything other that stereo out of it, and the receiver confirmed that that was what it was all it was receiving.

I came on the forums and found a few posts that helped, but don't seem to have completely cured the problem. I have uninstalled the Realtek Audio Drivers (as one post said) and I have found the setting in windows to get it the speaker set upto 5.1.

However is there a way of not having any speaker set up in windows 7? I am just not sure that it is set up correctly and passing the audio through properly now. If I watch something that is in stereo it says that it is "PCM" and the receiver still says that it is getting 5.1 (which it would as it is being told that the audio is 5.1 from windows). If I watch a film that is 5.1 or DTS it still just "PCM"?

I hope this makes some kind of sense, thanks for any help anyone may have.