In this session Stone-IT will give insight in the initial reasons for the Sint Antonius hospital to choose open standards, Red Hat Linux and other open source software. The focus will be in the first place on the integration of the Windows and Linux infrastructure and secondly on the strategy to replace all Windows servers and desktops with Linux. In the solution we choose with the Sint Antonius hospital, back end systems like Red Hat directory server and Zarafa groupware are replacing Windows Active Directory and Microsoft Exchange. Although Stone-IT is an independent open source company, it uses a few commercial products, like Red Hat, Zarafa groupware and SEP sesam backup software, to solve the business problems of it's customers.