writing bootable CD's, mime types in ubuntu

[Maurice F. Piller]

How does one burn a bootable cd in ubuntu using nautilus?  I downloaded the
daily warty-i386.iso file and want to burn a bootable cd.  

I read in another post that one can burn bootable cd's by right clicking on the
iso image file in a nautilus window and you should be presented with an option
to burn the CD.  I do not get this option.

If I right click on the warty-i386.iso file and select properties it says it is
type application/x-arc.  Which leads to another question, how to edit file mime
types in ubuntu? 

By the way, I'm trying to do this is on an ubuntu amd64 machine, I want to burn
the i386 version to install on a laptop.
--Chip