I use webcast as one of primary source of information to upgrade myself. Its rapid action upgradation (RAU) for you 
You can easily upgrade yourself to .Net technologies if you are aware of any object oriented language. Upgrading to C# would be easiest for JAVA professionals.
One excellent collection of .Net webcast series is at:
http://www.pluralsight.com/drjoe/webcasts/webcasts.aspx
.Net Framework 3.0 webcast series:
http://www.microsoft.com/events/series/msdnnetframework3.aspx
Modern Software Development Using C#: Develop in .NET:
http://www.microsoft.com/events/series/modernsoftdev.aspx?tab=webcasts&id=42420
Architecting Modern Desktop Apps in .NET:
http://www.microsoft.com/events/series/modernsoftdev.aspx?tab=webcasts&id=42418
C# for Java developers
http://msdn.microsoft.com/en-us/library/ms228358(VS.80).aspx
Converting Java Applications to Visual C#
http://msdn.microsoft.com/en-us/library/c6t6bsdk(VS.80).aspx
Visual C#
http://msdn.microsoft.com/en-us/library/kx37x362(VS.80).aspx
Visual C# samples
http://msdn.microsoft.com/en-us/library/z9hsy596(VS.80).aspx
Visual C# 2005 Webcasts
http://www.microsoft.com/events/series/msdnvisualcsharp.aspx
You can always go to Events and Webcasts and find webcast on other technologies/products you are looking for. At the same time I have to admit, its getting tough now-a-days to find your webcasts…!
Events and Webcasts Homepage: http://www.microsoft.com/events/default.mspx