Audio Streaming

I use WiFi2HiFi at the moment to stream music from my macbook pro to my iphone which i then plug headphones or speakers into to listen to my music. I now have a HTPC set up running windows 7 which is connected up to my surround sound system. I would like my music, and other sounds, from my macbook to play through my audio system. Anyone know of any software which works similarly to wifi2hifi but using a Windows box as the wireless receiver?

Cheers
Matt