does anyone know how to open up a download dialog box based on user click on a link. I do not want to open it in a browser rather just open a download dialog for user to download instead.

i found this site: http://www.nebulais.com/osdownloader/download.html

Does what I want but I it only works for certain formats.
I am trying to let user download a special type of digital image called mrSid images with ext. sid

here is thier website: http://www.lizardtech.com/

plse help thanks