mime type conflicts

[Matt H.]

I just noticed an unwanted behaviour with an .rpm file. Upon clicking the
link to download the RPM package, instead of getting the Save As dialog
box I get a Helix Screen as it tries to process it as a multimedia file.
Upon inspection of About:Plugins in Mozilla, the reason for this behaviour
is evidently due to the Helix Player plugin registering the "rpm" suffix
as mime type "audio/x-pn-realaudio-plugin" -- RealPlayer Plugin Metafile.
So the question is, how can I change this? I would like to be able to
simply left click an RPM link and get the Save As box pop up instead of
right-click/Save Link Target As. 

TIA
-- 
Matt