Here are some commands that you can use to backup your system prior to an upgrade. You can do this in case anything during the upgrade goes wrong, or you just don't like the new version.

First of all, to save time, you can run these commands to clean up a little first:

Code:
sudo apt-get autoremove
sudo apt-get autoclean
Now for the backup. Depending on how much free disk space you have, you might want different levels of compression, so here are a few options:

-No compression (fast, big file)
Code:
sudo tar -cv --one-file-system --exclude=/home/* --exclude=/dev/* --exclude=/proc/* --exclude=/sys/* -f /home/system-backup.tar /* && sudo chown `whoami`:`whoami` /home/system-backup.tar
-Medium compression (slow, small file) (recommended)
Code:
sudo tar -cvz --one-file-system --exclude=/home/* --exclude=/dev/* --exclude=/proc/* --exclude=/sys/* -f /home/system-backup.tar.gz /* && sudo chown `whoami`:`whoami` /home/system-backup.tar.gz
-High compression (very slow, very small file)
Code:
sudo tar -cvj --one-file-system --exclude=/home/* --exclude=/dev/* --exclude=/proc/* --exclude=/sys/* -f /home/system-backup.tar.bz2 /* && sudo chown `whoami`:`whoami` /home/system-backup.tar.bz2
When that finishes, you should have a nice backup of your current system.
I've found that it's always a good idea to do this before an upgrade, because the new version might be incompatible with your hardware. You can recover your system using a live cd, but unfortunately, the commands will be different depending on your system, so you can make a post here if you need help recovering your system.