Its lucky I *keep* my wife... I kept my nerd side buried in the closet until after we were hitched She had no idea what she was getting into

Joking aside...things are going better with me and Leopard.
I'm working with about 12 macs in a pretty diverse environment. Single Sign On is working for authentication but not for accessing shared drives and I'm hearing from people that its wide-spread, not just me.

I have to say that 90% of apps work...but as we all know its that 10% that we rely on and will drive you nuts when its broken. So far I have not touched the PPCs, just intels and I can say that without a doubt the best success has come from a "wipe and install" followed by "archive and install" ... I have had no luck at all (IE won't boot) after a regular upgrade. Despite common knowledge that an "upgrade in place" is always risky, it is what apple defaults to so please take caution.

Above all else, back up! Backup your entire home folder and you'll capture your personal preferences, files, etc. For a more comprehensive backup you can clone your drive with something like Carbon Copy Cloner or SuperDuper or simply make a copy of everything (it may not be bootable, but you'll have it). Then you can safely wipe and install...then copy over your user directory and you'll find most things as you left them.