Fitz welcome to the Seven Forums.
It is possible that the HDMI audio showing is for your video card as the 8800 GT does support audio over HDMI but ony when connected/configured like this,
Guide: 8800GT/9800GT/9800GTX Sound over HDMI (Now including Creative cards)
You can also locate the HDMI device in Device Manager and if present look up the DevID or VenID,
and see what it is attached to there.
One more thing, looking at that screen shot of yours you don't have the Realtek driver installed for the onboard audio, it is currently using the default Windows, which why it is showing as "high definition audio device" instead of as Realtek audio.