.NET Framework 3.5 SP1

The Microsoft .NET Framework is a software technology that is available with several Microsoft Windows operating systems. It includes a large library of pre-coded solutions to common programming problems, a runtime or virtual machine that manages the execution of programs written specifically for the framework, and a set of tools for configuring and building applications. The .NET Framework is a key Microsoft offering and is intended to be used by most new applications created for the Windows platform.

Download: Web Installer | Redistributable
Homepage: Microsoft .NET