For what it's worth, I can also verify what flyingernst was stating earlier. I have a Visiontek HD 4850 running audio and video into my Denon AVR-3806 receiver, running on Vista Ultimate SP1. When I configure my speakers for 5.1 and I run a speaker test, according to the graph I have Front Left, Center, Front Right, Rear Left and Rear right which all play correctly. When I switch to 7.1, it adds Side Left and Side right. If I do a test with it configured for 7.1, the Rear Left and Rear right no longer play, but Side Left and Side Right do. This is incorrect. And I know for damn sure my speakers are connected to my receiver properly.
Also, just an FYI, today Realtek released version R1.98 of their HD Audio Codec. The HDMI Audio driver is still at R1.97. I just did a fresh install of Vista with these drivers, and still seeing the same problem.
Does anyone know why my DTS Audio and Dolby Digital tests would fail? I just upgraded from a Visiontek HD 3870. When I ran these tests with the 3870 it would switch my receiver to the appropriate mode and play correctly...albeit only after installing the HDMI Audio driver. However, after installing the HD 4850 it will not play the tests and just gives me an error message right away. That being said, it does appear to be playing the audio correctly as I did test with my Transformers HD-DVD and audio was playing correctly out of my 5.1 setup.
Also, in case this helps anyone, I configured the audio properties on my PC in the Advanced tab to use "16 bit, 96000 Hz (Studio Quality)". Upon clicking the test button my receiver shows me the following output for 5.1 and 7.1 respectively -http://slap.gotdns.org/PCM-5.1.jpghttp://slap.gotdns.org/PCM-7.1.jpg