Which files do I need to copy?

In your user name home folder, there should be a "Library" Folder, inside that there is a Mozilla folder. Keep following that down and you will find Profiles, default, then another folder in that which should be your user profile. Don't mind that its named kind of funny. I'm not sure if you could copy the whole Mozilla folder, or just what is in your the Profile folder. Make sure you install and run Firefox, then close and make sure Firefox isn't running. Then copy over your profile info.

It could also be as simple as copying the cookies file and the bookmarks.html file. Just guess and test.

 

What type on install do you plan on doing, because the archive and install option will leave your library and application folder alone. Plus crate a folder for your old system, as a backup.

 

True sorry, its the morning here and i just quickly read your thread.