DVI-HDMI Audio

I have an nVidia 8800GTS graphics card on my desktop, and I'm connecting it to my Receiver via a DVI-HDMI adapter (which then displays the video on my 50" plasma). The video is fine but I'm trying to figure out a way to have audio go to the receiver as well. I tried setting my default sound playback to Digital Audio (HDMI) but the receiver is not getting it.

I did some poking around and someone's post said that it is not possible to do this with an nVidia card because they lack an audio chip. If this is true, does anyone have an ideas for an alternative option?

The HDMI input on the receiver does not have an option for sound coming from a different source (in other words, I need to figure out how to have both the audio and video come from the same HDMI cable). Has anyone come up with a workaround for a problem like this?