Transparent backgrounds

["Robert G. Brown" <bob@xxxxxxx>]

OK, all you graphics buffs, I've got what might be a simple question...

Using one of the graphics tools that comes with most Linux distros, I want to
take an image and make the background (assumed to be of one color, or darned
close) and make it transparent. A transparent background is one that allows
wallpaper or background (on a web page) to show through.

Telling me how to this on some other OS is not an answer. Telling me that you 
THINK it can be done in some way is not an answer. Telling me that you've
heard the GIMP does this is not an answer, and pointing me at something 
general is not an answer either. Been there, done that, bought the T-shirt. 
Please tell me how this effect can be acheived, what software is used, and
how it is employed.

I believe that someone who has really done this will be able to tell me in a 
snap, and I'm missing something either obvious or so obscure it's simply not 
funny.

                                                      Thanks and Regards,
                                                         ---> RGB <---