Which .NET Framework is best for Windows XP?

The .NET Framework is a software framework that runs primarily on Microsoft Windows. To run .NET Framework application, we need to install the related .NET Framework as prerequisite on the target machine to support it.. The most updated version of .NET Framework is 4.0 which is present in windows 7 as default. How ever .NET Framework 4.0 is supported on the following Windows XP related OS:
Windows XP Home Edition SP3
Windows XP Professional SP3
Below is the url which contains the system requirement for installing .NET Framework, its installation procedures, specifications and also the downloadable link. http://www.microsoft.com/en-us/download/details.aspx?id=17851