Reassociating launching apps from Fedora Linux / Gnome. FC4

[Clive at Rational]

Hi,

   Does anyone have a link to where the process of
associating a new application with a file type in
Fedora is described? For example, when I click on a
.jpg file on the Fedora desktop, by default "Eye of
Gnome Image Viewer" is launched. I want to chnage that
to launch "gThumb Image viewer" since most of the time
when I click on a jpg in a directory I want to
organise the files into some sort of photo album or
view them via a slide show. How do I change the
default application launched?

Thanks

Clive