With the advance of computer hardware and software techniques and the continuous growth of application requirements, the computing systems, which have computers as their centers, have increasingly broadened the scope of application, while the complexity is also growing quickly. The demand for evaluating and improving the dependability of computing systems is more and more urgent. This paper gives the definition of computing systems’ dependability, and a series of quantitative indicators are presented to evaluate the dependability.At the same time, the threats to system dependability are classified and analyzed in details. Since the traditional methods are incapable of dealing with the diverse dependability problem faced by the increasingly complex systems,people are constantly searching for new techniques. In this context, the virtualization technique comes to its renaissance, and is rapidly becoming a major research focus in recent years. In this paper, the existing research results on applying virtualization to enhance the dependability of computing systems are summed up, and the main characteristics and mechanisms of virtualization on enhancing dependability are introduced. But due to the restrictions of the existing computing systems architecture, the superiority of virtualization can not work fully.Service Oriented Architecture (SOA) meets the requirements of virtualization well for the loosely coupled, platform independence characteristics. Therefore, at the last part of this paper, a framework which integrates SOA and virtualization is proposed to enhance the dependability of computing systems, which is called Service Oriented Virtualization (SOV). This paper analyzes how this system framework can enhance the system dependability by mechanisms of virtualization and architecture superiority, when faced with many kinds of dependability threats.