An update to the Microsoft Windows SDK for Windows 7 and .NET Framework 4 (Windows SDK 7.1) is now available from the Microsoft Download Center. This update addresses the issue where Visual C++ Compilers and libraries that are installed with the Windows SDK are removed when Visual Studio 2010 Service Pack 1 is installed. 

Please follow this link to download and install the update.

For more information about this issue, please see the related article.