Whose bright idea was it to associate .RPM with RealPlayer??
 

I just tried downloading an RPM package, only to find that RealPlayer has taken over that extension. Now mozilla tries to open packages in a browser window. Is it just me, or should .RPM be one of those sacred extensions that NOTHING ELSE SHOULD USE?? So enough with the whining, how can I change file associations in Red Hat 8?

You could try looking in Edit->Preferences->Navigator->Helper Applications in Mozilla.

That should be where MIME types thingies are handled, so hopefully you can unset it there.