Are you using stable or etch in your sources.list? Lenny is the new stable, so if you're using stable in your sources.list, that would explain the big update.
I'd use etch, because otherwise you'll have a mixture of Etch and Lenny packages. If oyu want to upgrade to Lenny, take a look here: http://www.howtoforge.com/how-to-upgrade-a-debian-etch-system-server-and-desktop-to-debian-lenny
Hmm this sucks.. I do not really want to update that server, but I've selected Y when asked Now.. I have upgraded 84. So. How do I rollback to the setup before the 84 upgraded, and will it harm the system if I now use "Etch" only in the apt?