Need a header file that undefs all defines in windows.h

To be tidy, I want to #undef everything defined in windows.h.

E.G:

namespace os_stuff
{
    #include <windows.h>

    // ARGH! Macros everywhere!

    // at least I can keep the rest of the API in here
}

// include a bunch of files here that use the Windows API through os_stuff

namespace os_stuff
{
    #include <unwindows.h> // <- #undefs all that was #defined in windows.h
}

// All clean, as though windows.h was never here. Though os_stuff, used nowhere else,
// still has all of the API declarations in it (which is OK).