Translations:Faq/General/118/13/en
Method 2. Find "Set default programs" (how to get there varies between different versions of Windows and is not even standardised in other OSes either). It's often in a "control panel" or "system settings" or "system configurations", in Xp it's sometimes at the top of the "Start" button menu. If there's an option for "Office" then set LibreOffice.