Correct me if I'm wrong (I haven't poked around on my central in a while) but all the stuff on "drive0" is either music or local configuration. The kernel, etc, is contained in /.

I don't remember the exact partition layout off the top of my head, but it seemed to be designed so that during an upgrade, you could replace all of the kernel, but leave the music and configuration untouched.

Doing a backup of the root partition could be more complex given boot sectors, etc. It probably wouldn't be worth the effort given that you can just restore root off of the cd.