For those using Firefox, I would like to point out a truly premier utility: MozBackup. MozBackup will back up all your vital statistics for both Firefox and Thunderbird, and I can now attest to the utility of this ... er, utility. :)
Just last week, the S.M.A.R.T. routine in my computers' CMOS indicated that my data drive was bad, so I bought an external USB 2.0 drive, and backed everything up. Just for laughs, I also used MozBackup to backup my browser & email settings to the external drive as well.
...Come Monday night, all Hades breaks loose across the Midwest. I'm lucky in that that the power outage in my part of town was during my time at work. Alas, when I got home, I turned on my computer only to get the message NTLDR not found. Urk. Double-urk. Not good at all.
I was fortunate in that I had a spare 80Gb drive, and re-installed Windows XP. The challenges of installing Firefox & Thunderbird on the new drive, then restoring my old settings were daunting, but MozBackup restored Every.Single.Stinking.Thing; passwords and all. Amazing. Really.
Thunderbird was very nearly as painless, except for most recent email traffic, but that may be because my Roadrunner account hasn't seen much traffic. All local folders (I make a point of dumping everything over six months old to local folders) restored just fine. My gantry.net account seemed to restore just fine, showing everything back to January.
Bottom line: this sucker is officially Da Bomb for backing up your Firefox settings. Bookmarks, passwords, preferences, themes, plugins; everything. Really. I installed Firefox, ran the restore, and BAMB!, I was back. This was one of the most painless restores I've ever seen, and I go back to CP/M days.
If you use Firefox, this utility is a MUST USE. It's just that simple.