I sure as hell don't know. Well, I got the Windows CD player (w2k) registered as the default player for the AudioCD at the MyComputer level. Problem is, the eject buttons on vearious applications no longer worked. Windows CD player, the ripper program I'm using, right-click->Eject from File Manager ... nothing.
It's not a problem, though, because the next time I ejected (manually, had to use the paper-clip-through-the-pinhole trick) and inserted a new one, RealOne reaccquired the association.