I just had a problem at work whereby the version of office installed in the last 30 days needed activating and the product key was not working. Luckily we have several Office keys sitting in the server room so I set about trying to change the key on the machine without having to reinstall. This means you don’t need to uninstall/reinstall Office which will take half an hour. This took me 2 minutes

After a short Google search I came across a Microsoft article that told me exactly how to do it. Here are the steps I took:

1. Close any Microsoft Office Applications
2. Open the registry (Start -> Run -> regedit)
3. Find the appropriate office installation key under  HKEY_LOCAL_MACHINE \Software\Microsoft\Office followed by your version
   • Office XP ->…\10.0\Registration
   • Office 2003 -> …11.0\Registration
   • Office 2007 -> …\12.0\Registration
4. In one of the subfolders you will see a product name field. Select the subfolder with your Office name in it (IE: Microsoft Office 2003)
5. Delete the following key names:
   • DigitalProductID
   • ProductID
6. Close the registry (no need to look for a save button, there isn’t one!)
7. Open up any Office Application and you will be prompted for your product key and then to activate.

Thanks to Microsoft for writing a clear and concise how-to for a change without referring you to various knowledgebase articles. I used the following site for reference: http://support.microsoft.com/kb/895456