Given that the Registry is an essential component of Windows, and a damaged Registry can make Windows totally inaccessible, a good backup of the Registry is one of the most important safeguards you can employ.
Unlike Windows 98 and Windows Me, Windows XP does not come with a distinct mechanism that automatically backs up the Registry, which means you’ll have to implement one of your own to fully safeguard your Windows environment.
The Registry is stored in certain files (see Section 8.4 earlier in this chapter) on your hard disk, so you can create a backup by simply copying the appropriate files to another location.
When you start Windows, the information in the Registry is loaded into memory. While Windows is running, some changes may not be physically written to the Registry files until you shut down your computer; others, such as those made by the Registry Editor, are usually written immediately. For this reason, if you’ve made any substantial changes to the contents of the Registry, you may want to restart Windows before backing up the Registry to ensure that the files on the disk reflect the most recent changes.
The other consequence of using the Registry files is that you may not be able to simply use Explorer to copy them while Windows is running, and you certainly won’t be able to overwrite them. The workaround is to attempt these measures when Windows isn’t running, which means starting with the Emergency Recovery Console or with a set of boot disks, ...