Backup before upgrade

[Sigma1]

Hello,
I'm wondering if there's an easy way to backup my system files (i.e. everything except /home) before upgrading 11.10 > 12.04. My material is beginning to show its age, and I wouldn't want to end up with graphics issues and an unusable 12.04.
Can I, for example, just copy and paste the files in my system partition onto an external diskdrive and then, in case I have any problems, copy them back, use a live CD to chroot into the old system and run update-grub?
Thanks for any help you can give!

[msammels]

Please read this sticky.

[Sigma1]

Thanks for the answer, and the link... I read my way through some of it, but nonetheless managed to render my system unusable. chroot and update-grub didn't appear to work, to get grub straight, and I wasn't patient enough to experiment too long.
The long and the short of it is, I wiped the lot and reinstalled 11.04... I'd forgotten how much I liked the gnome desktop.