How can change the CD Key of my Office XP installation?

You can do it by editing the Registry। Apply this procedure:

Warning!

This document contains instructions for editing the registry. If you make any error while editing the registry, you can potentially cause Windows to fail or be unable to boot, requiring you to reinstall Windows. Edit the registry at your own risk. Always back up the registry before making any changes. If you do not feel comfortable editing the registry, do not attempt these instructions. Instead, seek the help of a trained computer specialist.

1. Locate your valid product CD Key, which is located on the back of the original CD case.

2. On the Start menu, click Run.

3. In the Open box, type Regedit, and then click OK.

4. In Registry Editor, find the following subkey:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\10.0\Registration

Click the plus sign (+) next to this folder. If you see only one subkey in this folder that has a 32-character {GUID} (globally unique identifier), select that subkey and go to step 5.

If you see more than one subkey that has a 32-character {GUID}, select each one until you find the one whose DisplayName value (in the right pane) matches your version of Office.

5. For the selected {GUID} subkey, select the ProductID string value in the right pane.

6. On the Edit menu, click Rename.

7. Type

OldProductID

and then press ENTER.

8. On the Registry menu, click Exit.

9. Start any Office program.

10. When the Microsoft Office XP User Information dialog box appears, type your valid product CD Key (located on the back of the CD case). Follow the instructions on your screen.

11. Return to step 4, select the Registration folder.

12. Right click Registration folder and select rename.

13. Type OldRegistration and press enter.

14. Follow steps 8 - 10.