Question: I have winXP LibreOffice and MS office installed.

How do I make LibreOffice the default opening program for all of its know document types?
I know that I can change one extension at a time. But is there a way to change all of them?

I want LibreOffice to open .doc .xls and ... (I do not know all of them)

Answer: 
'Modify' worked for me. Thanks!

On Windows Vista:

* click START
* Settings
* Control Panel
* Programs
* Programs and Features
* Uninstall a Program
* Select the right program from the list
* click 'change'
* follow instructions.
For me it worked to just use the "default apps" in windows system settings.

just hit start and type default apps