A lot of iTunes users would have installed the old quicktime component for ogg playback and enjoyed many hours of music playback through iTunes. I remember the fateful day when I clicked on Software Update and had QuickTime boosted to its new 7 version.
It was on that day that my Oggs died. 
Considering I had been buidling my iTunes Library for at least 2-3 years this was a massive blow to my ego and aural diet.
I reverted to using VLC, although more versatile in format playback, the user interface is far from ideal.
My second attempt at tracking down an ogg component to playback ogg files in Quicktime led me to this wonderful site owned by Arek Korbik. As I am running Panther Server I have yet to taste the Tiger experience, and thus ran into some problems getting the latest build to run, so any 10.3.9. users out there, use the r24 build.
Otherwise i’m fully ogged up and back into iTunes.
Now Apple only have to build ogg and flac support into the iPod !! Come on Apple !