Saving off configuration in Active Directory for a server rebuild

Is there anybody out there who is familiar with Active Directory on windows 2000 or 2003.

If a server rebuild is required or AD is corrupt then it will need re-installing but if you have a lot of users on the domain then all the accounts would need recreating etc which is a pain. Surely MS must have configured a save config feature in there somewhere or is there any configuration files you can just copy and overwrite and maybe reboot server bodge it and scarper style.

Any advise would be appreciated.

Dave P