Also, I would not try and learn C++ and GUI programming at the same time. If you want to learn C++, start that. If you want to learn GUI stuff, just start now with the WinAPI.
Like I said before, you are not closing the door on anything (that's Mario's job :p).
*I'm sure this perspective comes from people who have not spent any serious time doing anything but OO, so they are flabbergasted at the idea that doing without has it's own advantages and techniques.