putting shoutcast into soundcard mode you can use anything you like to play your music with and setting the soundcard to stereomix/waveout/allUhear will allow it to strea whatever runs through the pc.
eg decks / mp3 mixers /cd mixers etc
this will include windows noises and msn noises etc so you may want to turn them off
this tutorial might help,
there are other programs as mentioned in the post above like sam / simplecast / virtual djs and you should go to the manufacturer for support