Head to the Visual C++ Team’s blog entry entitled “MS11-025 Visual C++ Update Issue“, scroll down to the section entitled “Visual Studio 2010 RTM with Windows SDK”, and follow the instructions there.  For completeness sake, here they are:

If you have Visual Studio 2010 RTM and Windows SDK 7.1 installed on an x64 machine, then the Visual Studio 2010 update (KB2455033) fails to install on your machine.

Workaround The workaround for this issue: Go to Add/Remove Programs and uninstall the package “Microsoft Visual C++ compilers 2010 Standard x64″ Try installing KB2455033 again.