Playing music remotely

Does anyone know a way to play music on a machine from a remote location?
I've got wireless home network setup with a laptop running XP and a desktop
running Vista. File sharing works fine and I can access all of the music on
my desktop from my laptop. The desktop has a nice speaker system setup and
I'd like to be able to turn on music coming through those speakers from my
laptop. I've been using remote desktop and the music just plays through my
laptop. Any suggestions?