Can't believe no one jumped in on this one. Maybe no one backs up their registry and just believes Windows will always work correctly.
In my case I have two copies of the OS in a dual boot configuration - regular and minimal. I figure a registry restore will be needed whenever my regular OS is out to lunch. Therefore (1) on the regular OS I run rdisk to update the repair registry, and then (2) reboot on the minimal OS to backup (to tape) the '\repair' directory of the regular OS.
This will always allow me to boot my system to the minimal OS and restore the registry. Note: my backup configuration on the regular OS is different and non-compatible with the minimal OS, therefore I can not backup the '\repair' directory with the regular OS.
Your mileage may vary.