Is there a version of Cisco ACS that supports the Windows 2003 resource kit tools:
Network Access Quarantine Control
Remote Access Quarantine Agent service
They are used to ensure connecting remote users have certain hotfixes, service packs, etc...
The config documentation says a "you'll need a NAQC-compliant RADIUS server, such as the Internet Authentication Service in Server 2003, so that network access can be restricted."
Thanks,