For someone who has worked in the professional publishing industry, I rely on InDesign and Photoshop for creating professional documents, even if they're as simple as a business card. Sometimes I don't have the luxury of working with these expensive programs, however, so I look for alternatives that can get the job done. I'm familiar with GIMP vs. Photoshop, and in a pinch I can use GIMP, but prefer Photoshop because of a decade of experience with it.
I've used Quark and InDesign (and PageMaker before that), and consider InDesign the tool of choice for page layout.
I recently ran across an open source product called Scribus and wondered if anyone with Quark/InDesign experience has tested this, and can put forth a list of what it does and does not do by contrast.
(I've downloaded its installer and read through a small bit of the documentation but have not had time to do much with it yet.)