Windows – Play audio over network with Windows 7

I have seen software for Linux systems that allows me to send the audio from one system to another over the network, is there such a software (a driver likely) for Windows, specificly XP but Vista and Windows 7 would be best.

I'd like to stream audio (ALL audio, not just mp3s, etc) from my laptop to another computer over the network. I know that Windows Remote Desktop can play audio over the network pretty easily. Is this part of .Net that I could just code a simple app that streams the audio without RD'ing in? I also don't want to run it over an extra physical wire if possible.