Stereo headphone mini jack to stereo RCA, plug that into the audio in for the channel you're using, or if you've got an amp/hifi system you could chuck it into that.Jobs a good'un.
Mate its simple go in to your sound settings change ouput from laptop speaker to hdmi output simples!!! can be done via control panel or via speaker symbol on your task bar! http://www.sevenforums.com/attachments/sound-audio/10024d1241751362-no-hdmi-audio-out-windows-7-sound.png You will see this open when you are in sound settings simply select hdmi when you plug it in!