Run system restore to create a restore point first, then:
Use the Activation Wizard
Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
If you have only a few volume licensing product keys to change, you can use the Activation Wizard.
Note Microsoft recommends that you run System Restore to create a new restore point before you follow these steps. For information about how to create a restore point by using System Restore, see the "To Create a Restore Point" help topic in Help and Support.
1. Click Start, and then click Run.
2. In the Open box, type regedit, and then click OK.
3. In the left pane, locate and then click the following registry key:
4. In the right pane, right-click OOBETimer, and then click Modify.
5. Change at least one digit of this value to deactivate Windows.
6. Click Start, and then click Run.
7. In the Open box, type the following command, and then click OK.
8. Click Yes, I want to telephone a customer service representative to activate Windows, and then click Next.
9. Click Change Product key.
10. Type the new product key (re-enter your existing one) in the New key boxes, and then click Update.
If you are returned to the previous window, click Remind me later, and then restart the computer.
11. Repeat steps 6 and 7 to verify that Windows is activated. You receive the following message:
Windows is already activated. Click OK to exit.
12. Click OK.http://support.micro...kb/328874/en-us