VC++ 2012 RTM did not support Windows XP – that support came later in 2012 in Visual Studio 2012 Update 1.
The CTP of Windows XP targeting with VC++ 2012 could be installed, but you would have to link the CRT statically in order to deploy. See this blog article for more information.
Visual Studio 2012 Update 1 added official support for running applications built with VC++ 2012 on Windows XP as well as the ability to link the CRT dynamically.