CGT, Confederación General del Trabajo, Spain
The person who is writing this made an official proposal to change all of our computers, servers, desktop workstations, laptops, etc. in a period of two or three years to Debian. The proposal was accepted by the most of the local trade unions from all over Spain. The process began last year, and many local federations have just changed to Debian or distros based on Debian.
Our goal is not only to change the organization's PCs to Debian, but all of our affiliates' machines, too. Our organization has about 60,000 members and hundreds of locals with computers; we don't have exact numbers. The main uses of these machines are related to the office area: word processors, web browsing, and a bit of multi media.
We decided to choose Debian because Debian faithfully follows the GNU spirit, because of the DFSG (it is and will be free software), and easy maintenance with repositories of .deb packages, etc.