The purpose of this study is to clarify the mechanism of how software engineering capabilities relate to the business performance of IT vendors based on the continuous researches in 2005, 2006 and 2007. To end this, we developed a structural model, including the Software Engineering Excellence (SEE) indicator which consisted of deliverables, project management, quality assurance, process improvement, research and development, human resource development and customer contact. By analyzing the data collected from 100 major IT vendors in Japan in 2007, we reproducibly observed that the effort level on human resource development, quality assurance and project management made better performance of customer contact, research and development and process improvement of the IT vendors in Japan, as we found the similar tendency in 2006. However, the causal relationships differ significantly from the origins of the vendors, i.e., IT makers, IT users and independent vendors.