One of the problems with using Thunderbird for email and Firefox as a browser is that it is difficult to find the files to back up and more so to be sure that you have all the files you need. I came across this when I needed to transfer all settings and stored emails from XP to Windows 7.
Enter MozBackup, from http://mozbackup.jasnapaka.com/
It is freeware developed by Pavel Cvrcek from the Czech Republic and is how programs should be: no entries in the registry, just unzip and put the exe file where you want it. It finds installed copies of the various Mozilla programs (a lot more than just Thunderbird and Firefox) and when you click the one you want to backup it offers to deal with all the suitable settings but gives you the option to deselect, so you could use it to back up just settings, or just emails.
It then offers a backup file name suggestion (usefully incorporating the date) and offers a place to store it but you can change those.
I wondered whether it would work in reinstalling when copied to Windows 7, which puts the files in different places to XP. but it worked perfectly. There in Windows 7 was Thunderbird with all the settings and emails I had in XP. I then repeated the process for Firfox and again it just worked.
When I had a problem with Windows 7 and went back for a while to XP, the process worked in reverse — not a lost email or bookmark.
