I was doing a search yesterday and happen to find a freeware app that allows you to play media on your PC using your PPC as a remote:
Pocket PC Media Control
It has a very simple interface but seems to work quite well (even on X50v). Unlike Rudeo Control, it doesn't actually open WMP on your desktop when playing audio, but it makes use of the WMP playlists. I haven't used it much, but so far so good!
