I have it setup in a macrorecorder where if my computer is idle for 20min, it will delete cookies (can also specify cookies to keep) through CCleaner and backup my firefox profiles (can also specify segments to backup) w/ MozBackup.
Then that goes into a 2nd portable harddrive and a USB drive w/ synctoy through task scheduler.
I had a harddrive crash and it was the worst feeling ever. I takes around $900+ to replace the heads in most of them.
EDIT: Just realized that the above has basically nothing to do w/ what you said, but it brought up the memory of how important firefox is and how I prevent losing the data. I have sooo many bookmarks/plugins/settings it's insane. It's sad really.