Virtualization is no longer an "emerging" technology. Its potential to increase the efficiency of IT infrastructures has become widely recognized. Yet, virtualization also raises several key questions. Should virtualization be implemented only for new projects, or applied to existing infrastructures? Should opportunities be pursued on a case-by-case basis, or targeted as a broader goal of IT strategy? What level of investment should be made, for what return? What priority should be given to virtualization initiatives relative to the many other claims on IT resources? Before these questions can be answered, a broader understanding of the costs and benefits of virtualization at the enterprise level is needed. This report marks a first step in this process.