REGISTRY EDITOR PE
Menu location: GO > Programs > Utilities > Registry > Registry Editor PE

Registry Editor PE allows editing of remote registry hives from Alan's Boot CD. If you boot from the CD then run regedit.exe from the command prompt, you will view the registry of the boot CD and not registry of the local C: drive. You may import individual hives from the remote computer manually but this is cumbersome. When Registry Editor PE is started, all you have to do is choose the location of the Windows directory you wish to edit (usually C:\WINNT or C:\WINDOWS), then click "Open" on the default SAM, SECURITY, SOFTWARE and SYSTEM hives.

Note: You cannot view or edit a registry that is in use. For this reason, Registry Editor PE is disabled when running from Windows as opposed to the booted CD.