Multiple WMC instances can run at a time, all will be accessible to a client. Any UPnP AV client can be used to access WMC shared media. The client can query WMC for the list of files shared, the result of the query is formatted using XML.
Once it chooses from the list the media to be played, the media file is streamed to the client for playing. Pictures are streamed using HTTP, different protocols are used for music and video. A client supporting the UPnP Media Renderer standard will be able to render the stream.