choosing default applications (Re: playing and ripping, ogg and mp3s?

[Philippe Landau]

Jeff Waugh wrote:
>> On one of my other systems Gnome has an application for 
>> "File Types and Progams" listed under the Gnome Preferences menu.
>> I cannot find any similar program on the Ubuntu desktop 
>> for checking File type association.
> Right click on a vorbis file and change the default association 
> (open with other application, then you can 
> change it for all types in the properties dialogue).
- how can i find mozilla composer when i choose "open with ..." ?
- is the file type determined exclusively by the file name extension ?
- when i click on a http link sometimes gnome
   opens the page in firefox, sometimes in mozilla browser,
   can i change this ?
   (i also need to change preferred email reader to thunderbird).

kind regards     philippe