This document summarizes a presentation given by Mel McIntyre on using open source software for geographic information systems (GIS). McIntyre discusses their experience developing Health Atlas Ireland, a web application using open source GIS and statistical components to support health services planning. Examples shown include administrative boundary maps, deprivation indexes, population maps, and catchment analysis tools. Technical aspects covered include the open source software used, architecture with OpenLayers, PostgreSQL/PostGIS, and Python/Zope. Barriers to and strategies for adopting open source software are also outlined.