.NET Framework Library Source Code

Now you can debug into .NET Framework Source code with Visual Studio 2008.
Source code is available for following libraries:

• NET Base Class Libraries
  

• ASP.NET
  

• Windows Forms
  

• Windows Presentation Foundation
  

• ADO.NET and XML

Microsoft Reference
Detailed explanation about how to enable this.
Stepping into .NET Framwork Library source.
Debugging .NET Framework Library source.