wxWidgets is pretty cool for multi platform free stuff. There is a pretty nice visual compiler called wxDev-C++. The one bad thing about wxWidgets is that it is bulky and is all 3rd party so some things aren't all the way there, its not the most supported. Programs like VLC media player and audacity use wxWidgets. With wxDev-C++ the exe seems to be kinda big.
I looked a little bit at QT and it just seems kinda weird, and I believe you need a license for it. I didn't look into it too much.
I would suggest learning the windows programming, you will probably be much better off. Get Visual Studio and maybe a nice book and play around.
Or.....
You can learn some C#, from what I hear C# and the .net framework are very easy to use and are good for GUI applications. One plus side to C# is all the memory management is done inside the .net framework so you don't have to worry about memory leaks as in C++. With C# you cant do things with memory though as you can in C/C++ though.
So it all comes down to personal preference. C# may be easier but I think it is a bit more restricted compared to C++ and with C++ you will probably be writing and debugging more then C#. I don't know too much about C# but this is just what I have heard
