IPsec Policy Agent
Windows Vista Service Details
Required if internet provider requires it. I do not believe that many do, but some organizations might, so ask around. Or, disable it and test network connectivity.
Enforces IPsec policies created through the IP Security Policies Snap-in or the command-line tool netsh ipsec. If you stop the service, you may experience network connectivity issues if your policy requires that connections use IPsec. Remote management of the Windows Firewall will not be available if the service is stopped.
Consequences of Stopping:
All services listed in 'Required For' will be unable to function