This document summarizes the city of Zaragoza's experience migrating desktops from Windows to Linux between 2005 and 2013. It outlines the need for a migration plan, prototypes tested including SUSE and Ubuntu, and an eventual migration of 2500 PCs to Linux with 700 remaining on Windows. Key lessons learned include the importance of project management, allocating proper resources, support from top managers, and long term support from the Linux community. The city created AZLinux as a local Linux distribution and support program.