Recently I recorded this TechNet webcast focusing on the new network diagnostics built into Windows Vista:

http://www.microsoft.com/winme/0702/20430/index.html 

This webcast focuses on the Network Diagnostics Framework (NDF) and the Network Connectivity Status Indicator (NCSI).  These features will help you determine if you are connected to a local network and the Internet, and get you re-connected when there are common problems.

This webcast is slightly more technical than the Support webcast that I recorded in December.