Presentation at the November 2004 ECAR Symposium. Open-source software (OSS) is not a fad—it is here to stay. While OSS provides additional choices and may lower software development and deployment costs, it is not free. OSS is changing the vendor environment, and it will be important to understand who will win and lose, as well as what the future vendor environment will look like. This session from leading industry advisor Burton Group will define OSS, identify its risks and benefits, review a market assessment and vendor software revenue models, and make recommendations for IT practitioners who are trying to make sense of OSS solutions.