How to get 5 1 output from hdmi

[TeHKasperek]

I have a Asus A8N-SLI Premium mother board, and I recently installed an gigabyte Radeon HD 6450 512mb DDR3 video card. I have the HDMI plugged into my surround sound and the output from the surround sound to the TV. I am having trouble getting 5.1 from my computer. It seems to only output stereo, is there a way to change this?

 

[gamerk316]

Set the output to 7.1 from the Windows Control Panel -> Sounds tab.