how do i make a backup of my system registry?

i use registry mechanic..

Make sure your logged in as an administrator then just got into the registry editor…
1.  Go to START->Run…
2.  Type “regedit” (without the quotes) and click the “Ok” button or press the enter key

Now export the registry…
1.  Go to File->Export…
2.  There are two radio buttons at the bottom of the export dialog.  Make sure the radio button for “All” is selected
3.  Give the file a name and click the “Save” button of press the enter key.

There you are your registry should be backed up.