APIs

I want to get into software development. I know the various languages most companies use, and new languages are fairly easy to pick up. The problem I have is working out what APIs and interfaces I should be learning. I've spent time poking around MSDN, but it's a huge place and I've no idea where to start. What are the key things I should learn about .NET, WPF, ASP and the like, and what are good tutorials/ guides/ books you would recommend to learn them?

>>4
NULL jokes aside, Win32 is not harder than POSIX. There are just more APIs because it has everything: filesystem, graphics, text, other UI stuff, etc. Compare it with POSIX+OpenGL+FreeType+... and you will see what's really harder.