In Windows Explorer, find one of the file types (ogg, mp3, etc.) and right click on it, then in the popup go to "Open With", and go to the bottom of the popup and select "Choose another app" or "Choose default program" (depending on which Windows version you have). Check the box "Always use the selected program to open this kind of file" or "Always use this app ...", and then select JRiver Media Center program.