samba - Dec 2002 - Backing up Windows 2000 PDC, disaster recovery

Hello,

I haven't been able to find much information on this topic and maybe some of
you can help.

I have a Windows 2000 PDC. I'm just trying to figure out some disaster
recovery procedures.  What do I need to backup on this machine in order to
restore another machine as the same PDC in case it fails?

As far as I understand I need the user database. Where is this actually stored
and can I restore a machine just by copying it back in? What about SID
issues?

Thanks for any help,

Viraj.