How to make a backup of the Registry?

WARNING: When editing the Registry, there is the risk of corrupting installed software or the operating system, which may result in data loss.
For Windows XP:

1. Click the Start button, and then click Run.
2. In the Run window, type regedit and then click the OK button.
3. In the Registry Editor window, on the menu bar, click File.
4. Click Export.
5. In the Export Registry File window, under Export range, click the All radio button.
6. In the File name box, enter the name for the exported file and then click the Save button.
7. In the Registry Editor window, click the X button at the upper-right to close the Registry Editor.
For Windows Vista:

1. Click the Start button, and then in the Search field, type regedit.
2. Press the Enter key.
NOTE: If prompted for an administrator password or a User Account Control prompt is displayed, type the appropriate password, click Continue or click Yes.

3. In the Registry Editor window, on the menu bar, click File.
4. In the File menu, click Export.
5. In the Export Registry File window, under Export range, click the All radio button.
6. In the File name box, enter the name for the exported file and then click the Save button.
7. In the Registry Editor window, click the X button at the upper-right to close the Registry Editor.
For Windows 7:
1. Click the Start button, and then in the Search field, type regedit.
2. Press the Enter key.
NOTE: If prompted for an administrator password or a User Account Control prompt is displayed, type the appropriate password, click Continue or click Yes.

3. In the Registry Editor window, on the menu bar, click File.
4. In the File menu, click Export.
5. In the Export Registry File window, under Export range, click the All radio button.
6. In the File name box, enter the name for the exported file and then click the Save button.
7. In the Registry Editor window, click the X button at the upper-right to close the Registry Editor.