I just ran a 35-foot HDMI cable from my desktop's video card to my new TV, extended the computer desktop to the TV (as a second monitor), and fired up Windows 7 Media Center. Then I noticed two things ...
I tried to search through Google, but all the options pop-up as sound not working through HDMI. I have a case where I am connecting an AV adapter to a TV, but sound is not working for video ...
The distinction between various flavors of HDMI can get a bit technical.