Please find below some of the important links which have been collated on Microsoft Core .NET Platform.
.NET Framework Conceptual OverviewThe .NET Framework has two main components: the common language runtime and the .NET Framework class library.The common language runtime is the foundation of the .NET Framework.
About Microsoft .NET 3.5 FrameworkMicrosoft .NET Framework version 3.5. Framework is an integral Windows component that supports building and running the next generation of applications and Web services. The key components of the .NET Framework are the common language runtime (CLR) and the .NET Framework class library, which includes ADO.NET, ASP.NET, Windows Forms, and Windows Presentation Foundation (WPF).
.NET Framework 3.5 ArchitectureThe architecture of the .NET Framework version 3.5 and 3.5 Service Pack 1 (SP1) builds upon the earlier versions of the .NET Framework.
.NET Framework System Requirements - System Requirements for Version 3.5 - System Requirements for Version 2.0 - System Requirements for Versions 1.0 and 1.1 Official downloadsMicrosoft .NET Framework 3.5 Service Pack 1.NET Compact Framework 3.5 RedistributableWindows Installer 4.5 Redistributable Microsoft .NET Framework 3.0 Redistributable Package Microsoft .NET Framework 2.0 Service Pack 1 (x86)Microsoft .NET Framework Version 2.0 Redistributable Package (x86) Public Sector Developer WeblogDownload the .NET Framework 3.0 Runtime Components.NET Compact Framework API DocumentationActiveSync 3.7.1Windows Mobile-based Smartphone 2003 SDKIntroducing the .NET Micro Framework Building Devices for Windows SideShow with the .NET Micro Framework Porting the .NET Micro Framework .NET Compact Framework Downloads
Resources
BCL Team Bloghttp://blogs.msdn.com/bclteam/archive/2008/11/04/what-s-new-in-the-bcl-in-net-4-0-justin-van-patten.aspx
Community Blogshttp://weblogs.asp.net/communityblogs/archive/tags/Web+Services/.NET+Framework/default.aspx
Aaron Ruckman's Web Loghttp://blogs.msdn.com/aaronru/archive/2008/01/19/installing-net-framework-3-5-language-packages-with-the-core.aspx
Wenlong Dong's Blog http://blogs.msdn.com/wenlong/archive/2008/09/07/net-4-0-wf-wcf-and-oslo.aspx
Wikipedia - .NET Frameworkhttp://en.wikipedia.org/wiki/.NET_Framework
Architecturehttp://en.wikipedia.org/wiki/.NET_Framework#Architecture
Standardization and licensinghttp://en.wikipedia.org/wiki/.NET_Framework#Standardization_and_licensing
.NET Framework 3.5 http://en.wikipedia.org/wiki/.NET_Framework#.NET_Framework_3.5
.NET Framework 4.0 http://en.wikipedia.org/wiki/.NET_Framework#.NET_Framework_4.0
.NET vs. Java and Java EEhttp://en.wikipedia.org/wiki/.NET_Framework#.NET_vs._Java_and_Java_EE
Microsoft .NET new logo and brandinghttp://www.uxpassion.com/2008/10/new-microsoft-net-logo-and-branding/
.NET Framework Developer Centerhttp://msdn.microsoft.com/netframework/
.NET Framework TechnologiesData Platform Development using ADO.NET http://msdn.microsoft.com/hi-in/data/default(en-us).aspx
Getting Started with ASP.NEThttp://msdn.microsoft.com/hi-in/asp.net/default.aspx
Base Class Libraries Communityhttp://msdn.microsoft.com/hi-in/netframework/aa569603(en-us).aspx
.NET Micro Frameworkhttp://msdn.microsoft.com/hi-in/netframework/bb267253(en-us).aspx
Windows CardSpacehttp://msdn.microsoft.com/hi-in/netframework/aa663320(en-us).aspx
Windows Communication Foundationhttp://msdn.microsoft.com/hi-in/netframework/aa663324(en-us).aspx
Windows Client.NEThttp://windowsclient.net/
Windows Workflow Foundationhttp://msdn.microsoft.com/hi-in/netframework/aa663328(en-us).aspx
.NET Framework 4.0http://channel9.msdn.com/tags/.NET+Framework+4.0/
Parallel Programming with .NET:.NET Framework 4.0 Poster for Downloadhttp://blogs.msdn.com/pfxteam/archive/2008/11/03/9037931.aspx
Sandboxing in .NET 4.0http://blogs.msdn.com/shawnfa/archive/2009/05/22/sandboxing-in-net-4-0.aspx
Tools and Utilities.NET Tools and Utilities http://www.c-sharpcorner.com/Resources/Tools.aspx
WPF Toolkithttp://sweux.com/blogs/smoura/index.php/wpf/2009/04/15/introducing-the-wpf-toolkit-datagrid/
What build tools are available for .NET?http://windowsclient.net/blogs/faqs/archive/2006/05/26/what-build-tools-are-available-for-net.aspx
CLR Profiler for the .NET Framework 2.0http://www.microsoft.com/downloads/details.aspx?FamilyID=a362781c-3870-43be-8926-862b40aa0cd0&DisplayLang=en
Fx Cophttp://msdn.microsoft.com/library/bb429476.aspx
Performance Console (PerfConsole) 1.0http://www.microsoft.com/downloads/details.aspx?familyid=5a04ee30-6259-4fad-bf05-ccb72be09b4a
.NET Productivity Suite http://www.ideablade.com/downloads.html?referrer=MSDNForms
ILMergehttp://www.microsoft.com/downloads/details.aspx?FamilyID=22914587-b4ad-4eae-87cf-b14ae6a939b0&displaylang=en
LibCheckhttp://www.microsoft.com/downloads/details.aspx?familyid=4b5b7f29-1939-4e5b-a780-70e887964165&displaylang=en
CLR Profilerhttp://download.microsoft.com/download/a/b/d/abd115c6-a96e-4d8d-b7de-9480deb6cd5c/clrprofiler.exe
Windows Communication Foundation Tools http://msdn.microsoft.com/en-us/library/ms732015.aspx
Windows Presentation Foundation Tools http://msdn.microsoft.com/en-us/library/ms742404.aspx
Windows Workflow Foundation Toolshttp://msdn.microsoft.com/en-us/library/ms734408.aspx