How to Back Up Windows Vista Registry Files
Before you start spelunking through your Registry, you need to back it up. If you know how to back up the Windows Vista Registry, you can undo most damage that you might accidentally cause by modifying the Registry by hand. If Windows heads south, you'll save yourself a lot of time if you have decent backups at hand.
Although there are a lot of ways to improve your system in the Registry, subtle slips can cause major problems. Take the time to research any planned revision to ensure that you have the precise instructions before trying to modify the Registry.
The Registry can store keys and values in many different ways, but to back up the Registry, you really need to be concerned with only two:
A .reg file is a text file that contains Registry entries. You can pick a Registry key and have the Registry Editor copy all the keys and values contained in that particular key into a text file.
So before you change a Registry value, create a .reg file and then keep the original .reg file as a backup. Restoring from the backup is easy: When you double-click the .reg file, entries in the file overwrite corresponding entries in the Registry. So if you save a .reg file as a backup for a key, mess up something in the key, and then double-click the .reg file, your mistakes are overwritten with the original entries.
A hive is a bunch of Registry entries stored as a binary file. (Don’t be intimidated: A hive is just a bunch of keys under a single key. It’s roughly analogous to a folder.) Because you can’t make changes to them by hand, they are harder to use (but they do have some benefits over .reg files).
Follow these steps to create a .reg backup file:
Choose Start, type regedit, and press Enter.
That puts you in Vista’s Registry Editor.
On the left, double-click down the tree to navigate to the key you want to save.
Typically, that’s the key you’re going to change.
Click once on the key you want to save.
The Registry Editor asks for a filename and location.
Give your .reg backup file a name, pick a good location for it (usually the desktop so it's handy for a quick repair), and click Save.
If something goes haywire, double-click that saved .reg file to go back to your original settings.
To be on the safe side, you should also create a system restore point before messing with the Registry. That way, if the wheels fall off and you crash Windows utterly and completely, you can restore the Registry to the point just before you started fiddling around (or use the Last Known Good Configuration option on the system boot menu if you can’t get Windows to boot).