Recently my team published a whitepaper on the Network Diagnostics that we built into Windows Vista.  The target audience for the paper is IT Professionals. 

The paper covers the Network Diagnostics Framework (NDF) and the Network Connectivity Status Indicator (NCSI) in depth including related registry keys/values and event log IDs.

http://www.microsoft.com/downloads/details.aspx?FamilyID=1698e42b-03fd-4cd9-b568-d948de55b0f8&displaylang=en

This is a great resource if you really want to get the most out of these features.