I would like to propose a much better solution. How do you intend to control the mouse pointer, and keyboard to navigate on your PC while looking at your TV? It seems like a much better option would be to buy a used Small Form Factor Dell Optiplex 780 from Ebay (typically around $100) then add in a ATI Radeon video card for around 30-40 bucks that has an HDMI out. This will be how your audio and video go through your surround sound system or straight to your tv. Then get something like this
http://www.amazon.com/Rii-Wireless-Touchpad-Keyboard-Android/dp/B00B9996LA to control your PC comfortably from the couch.
Basically what I am saying is for 200 dollars at the most, you can have a much better solution to your problem. You will have a dedicated media device, and optionally you can use it as a media server and run music and video stored on it to your other devices. I use mine to run netflix, youtube, hulu, and windows media center for all downloaded content stored on the hard drive.
I have a gaming PC about the same distance away from my TV that you do, and I just don't see how I would get a very practical benefit to running an HDMI cable to my TV from it.