Xbox 360 to dvi- video works great now need sound

I bought a normal hdmi to dvi adapter and the video works great on my computer monitor. But now all I need is audio. I took of the plastic cover on the standard xbox 360 a/v connector that comes with the xbox 360. I connect the hdmi cable and grey audio/video cable at the same time and then connected the audi to my reciever but it will only select the standard audio/video connector and not hdmi. So i have no video and only audio if i plug in both hdmi and grey connector. How do i connect the hdmi to dvi connector and get sound? Im willing to rig something up. maybe i can cut the video cables on the xbox 360 connector so that i can only get audio and use the video from the hdmi. I have to xbox360 connectors so i can spare one. I need a solution please.

source: http://www.youtube.com/watch?v=V9sJ-_l9zBM

The first cable is HDMI (from XBOX) to DVI (to monitor) cable. You can buy it from local electronic/games/console store. this cable is for graphic ONLY. thats mean you only can get the visual with no sound. this is because normal LCD Monitor didnt come with built-in speaker.

For sounds system, you need Optical/RCA Audio adapter and you need normal audio converter to convert the sounds from XBOX to your PC Speakers. with this converter, you can hook up your PC speakers to XBOX, and wallah! now you get the sounds from your XBOX.

Conclusions:

1) first cable is for converting HDMI ouput from XBOX to DVI input for LCD Monitor.
- common

2) 2nd cable for converting sounds from XBOX to your PC Speakers.
- sources include Optical/RCA Audio adapter on xbox site.