"Understanding Windows CardSpace: An Introduction to the Concepts and Challenges of Digital Identities"
Windows Server 2003. This also requires that the .NET Framework version 3.0 or 3.5 and Internet Explorer 7 be installed. .NET Framework 3.0 (or 3.5) is always required to run Windows CardSpace because it contains the core CardSpace system components. They also install components that CardSpace requires: the Windows Communication Foundation and the 2.0 Common Language Runtime. Internet Explorer 7 (IE7) is necessary because it has support for the Information Card