The receiver definitely does HDMI audio - it's the Onkyo 705. I'm running a DVD-R and my cable box to it through HDMI. The laptop is a Dell Studio 17 with the Intel GMA 4500MHD video controller.
Spent a couple hours on the phone with Dell support, searched many online discussions, performed many driver updates, confirmed and re-confirmed settings...nada. Should work as far as I know, so I'm suspicious of the HDMI-DVI connection to the TV - wouldn't be the first weird HDMI handshake issue I've seen.
No biggie right now, I'm going VGA to my TV for video and optical to the receiver for audio.