Hello,

As far as I know:

Epsilon forums around 1999, which seemed to be a service like EZboard. There was only one forum.
Early 2000, maybe late 1999, there was an own forum on this server. This was a very basic one without accounts.
Then around April 2000 it changed to a board like PHPBB (not sure what it was though).
Org changed host (?) late summer 2000 and we got UBB. That forum had pros and cons and we started to backup content as we already lost a lot (there wasn't an option really).
Changed to Ikonboard in Fall 2002. For the first time we could convert the forumcontent to this new board.

UBB and Ikonboard are PERL forums, a very nice language, but PHP works faster.
Changed to VBulletin during Summer 2003 and imported all forumtopics, including ones from backups that had to be prunned. Some server hiccups demanded a prune of the Backroom, those topics are still in backup.