This paper describers the steps we followed to complete the "i-muse(tm) - Interactive Museum" project, the first product of our startup entrepreneurial project now hosted at the Politecnico di Milano. The i-muse(tm) system is a combination of an innovative software product, PDA mobile device hardware and related support service aimed to enrich the user experience of people visiting museums and art events. We describe the evolution of the project, from the birth of the idea to the feasibility study, the workgroup organization and management, the software design, the technology evaluation, the software architecture construction, the multimedia contents production, the market analysis and the marketing plan we employed to promote it in the Italian and international market. Particular attention is dedicated to the usability testing phase we performed with the collaboration of the Educational Silk Museum of Como analyzing the results of the test of the PDA guide with different typologies of visitors and their reactions to the accessibility options we implemented in the user interface.