Actually this is a better document....
http://docs.info.apple.com/article.html?artnum=301270
I did the archive and install this time and (unlike previous times) have had little issue. Note the ""Preserve Users and Network Settings" option...select that and you'll find that most (if not all) of your preferences and network settings come across....so you just start up and keep working...no need to do reinstalls of apps....maybe just some 10.5 specific updates.
There was a post in another thread that said that "Archive and install" was a bad option....previously with issues I have then done a clean install....but things seem to be great on 2 machines that I've done this option.
Phil