This seems like a weird problem to me. afxcontrolbars.h
is certainly included in a standard VS 2008 installation. The only way you might be missing MFC components is if you installed the Express version, which doesn't come with support for MFC.
The first thing I would do is check to see if I could create and compile a brand new, blank MFC app using one of the built-in templates. If that works, there's something wrong with your project's properties.
Also check manually in the \Microsoft Visual Studio 9.0\VC\atlmfc\include
directory to see if you can locate the header file before you try to manually re-install the platform SDK. It may be as simple as Visual Studio not being able to locate the file. To remedy that, open the Options dialog, expand the "Projects and Solutions" tree, select "VC++ Directories", select "Win32" and "Include files" from the combo boxes at the top, and ensure that $(VCInstallDir)atlmfc\include
is included in the list:
Of course, the ribbon control (and other ribbon-specific items) weren't added to VS 2008 until the MFC Feature Pack. You will need to download and install that in order to compile applications that take advantage of those features in VS 2008. You can download the Feature Pack here for free.