Windows Live vs Kerberos

[royend]

Hi.
I am doing a report on Web authentication and have come over the
Windows Live login-service, which basically is a PKI (public key
infrastructure) where live.com acts as the KDC (Key Distribution
Center).

Can someone tell me differences between Windows Live and Kerberos?
Is it possible for instance to sat that Windows Live uses as its basis
the Needham-Schroeder protocol, the same way as Kerberos does?

I believe that Kerberos is a more general protocol which is used in
network authentication, as Windows Live is a special service for web
sites, gathering all users at a single sign on (SSO).

Looking forward to your answers!