Microsoft NAP is an effective network gatekeeper for Windows endpoints, but initial configuration is complex, policies are basic, and reporting is absent. NAP comprises client and server subsystems with an enforcement architecture based on 802.1X, DHCP, or VPNs together with VLAN assignment within the network to isolate devices when appropriate. NAP services are provided in Windows Server 2008, with Windows Server 2008 R2 adding a few capabilities to the NAP support. Microsoft continues to develop new features for NAP and related security functions. A number of the improvements in Windows Server 2008 R2 (download) make NAP deployment smoother: specifically the automated setup of the logging database, and multiple out-of-the-box configurations for the System Health Validator (SHV).
More info: Computerworld