Microsoft tries to work with vendors to make their products compatible with the Windows Security Center. The product must be registered with Windows Security Center for its status to be reported to NAP for a validation check. As for how far out of date a definition file can be, NAP does not provide for this. APIs are available to developers so they can develop SHA’s (System Health Agents) to work with NAP to says the software is up to date or not.
For a listing of Network Access Protection Partners: http://www.microsoft.com/windowsserver2008/en/us/nap-partners.aspx
Class: 6421A Configuring and Troubleshooting a Windows Server 2008 Network Infrastructure