Having Office 2007 and 2003 together in the same windows installation

Especially power users, have more than one version of Office installed on their computers. I will show you how to configure your office installation so you can use both office 2003 and 2007 together so you won't see Windows Installer messages when switching between different versions of Word or Excell.


This will force a particular version of Word to not claim the file extensions back.
 
First of all you have to install first the oldest version of office (eg. Office 2003).
Then inslall the newer version of Office (eg. Office 2007) clicking on customize instead of upgrade.


The main trick comes now:
1. Close all opened Word windows.
2. Open Word 2007 and let the setup run (if it appears), then close Word.
3. Open the registry editor and navigate to HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Word\Options
4. Add a DWORD named NoRereg set to 1 

Note: 11.0 refers to Word 11, which is Word 2003. Word 2007 is Word 12. To make Word 2003 the default and not 2007, use the same steps but interchange 2003 and 2007, as well as 11.0 and 12.0