Backup up your /home directory onto some external media such
as a USB thumb drive. I backup my /home directory regularly
and my entire / with a PCLinuxOS Live CD once a week.
The practice has certainly saved my bacon (and data) on more
than one occasion.
If you need to re-install, simply do it and recover the important
bits from the backup.
Of course, when I see a large update or ones that have obvious
system files, I do a / backup first. Just in case...