CentOS 5 :: Rhythmbox And Shoutcast Should Just Work But Plugins Needed Instead

I use shoutcast to select streaming audio stations to play, depending on mood,whim, whatever.when I click on 'tune in' next to the audio station, rhythmbox pops up....and that's that. I would expect it to just start playing the station.If I select 'Radio' in rhythmbox's upper left panel, and -then- click 'tune in' on the shoutcast page next to the station I want, there's an entry made in the playist at that time, but then there's an error popup says: Couldn't Start Playback You do not have a decoder installed to handle this file. You might need to install the necessary plugins. Which is surprising. It's a shoutcast stream. It should just play. But anyway, I guess something didn't get installed in the default install.