Don't know would it be useful but anyway. I use these files in order to play (place them in system32 during unattended):
1. Quick Time v6:
QuickTime.ax (register as other codecs through .reg or .bat-.cmd files)
2. Real Plyaer 8-9:
RealMediaSplitter.ax (register as other codecs through .reg or .bat-.cmd files)
These work on all files I tried. But there is no support for Internet I guess. There are about two more files to add for this (I don't need it as I download media files first).
By the way try this very interesting application from Linux World: Mplayer v1.0pre5 at
www.mplayerhq.hu/MPlayer/releases/win32-beta/ (there is a Windows version). It replaces most codecs and plays stream from Web. It is for command line (there are some GUIs available) but it is really universal and easy when you get used for two or three commands (I automated it by including them through .reg file during unattended