I've recently migrated my wireless network from RADIUS/IAS on Windows 2003 with PKI to Windows 2008 R2. It took me a while to get to the bottom of it so I thought I'd write a How-To to help others out.
# One or more 802.1X-capable 802.11 wireless access points (APs).
# Active Directory with group policy
# One or more Network Policy Server (NPS) servers.
# Active Directory Certificate Services based PKI for Server certificates for NPS computer/s and your wireless PC's