This will...assuming it`s nt/2000/xp...


Click Start > Programs > Accessories > System Tools > Backup.
Click Advanced Mode.
On the Welcome tab, click the Backup Wizard (Advanced) button.
Click Next.
Select Only back up the System State data, and then click next.
Click the Browse button.
Click Cancel if the "Insert Disk" warning message pops up.
In the Save As dialog box, choose a location to save your registry back up.
Click Save.
Click Next.
Review the information in this window. Your Contents should say "Back up only the system state." Click Finish.
When the back up completes click Close.
Your registry is now backed up. You may close the Backup Utility window.

Win9x

Click Start, click Run, type scanregw, and then click OK.
When you receive a prompt to back up the registry, click Yes.
When you receive the "Backup complete" message, click OK.

I used this link as quick reference BTW...

Symantec