what should I learn?

I want to develop rapid applications but they can perform more advance functions . do you think windows api is waste of time to learn?? cause I Microsoft introduces .NET and almost everything can be done with .NET now. so C#+.NET is a best solution. so what's the point with C++ + with GUI Applications?
I found out QT is easy to learn and since it allows to develop closed source applications under LGPL without paying for nokia why anyone go with Windows API?