For some years now it has been possible to run an enterprise, end-to-end, entirely on Free, Open Source software. Having proven the model with a £70 million pa company in 2002, Sirius have shown the way to increasingly larger businesses leading to their current work with household names like Specsavers and Standard Life. Using Specsavers and similar companies as the model, Mark will explain how to migrate to an entirely Open Source infrastructure, gaining performance, reliability and capability, whilst losing costs, maintenance problems and licensing woes.