I read up on the Mozilla support forums for experiences other folks have had upgrading. The general message I got was simply to uninstall the old version and install the new one. I tried that and it worked just fine.

I have one problem with the new version, and I'm beginning to think this is a concious effort on the part of the programmers: why can I never move things in my toolbars? It's the same in IE. They like to put their advanced search boxes flush to the right of the screen, and it simply gets on my nerves. .7 had it aligned to the left, which looked much better and was so much easier to use. It's just plain un-ergonomic. GRR.

*edit*
View the attachment. That's what I'm talking about.