First of all, there's a difference between Win32 and OpenGL. OpenGL is a graphics API for rendering triangles, while Win32 is a system API for stuff like showing windows, taking input, etc. The opposing API to OpenGL is DirectX, and I certainly wouldn't say it's inferior. Likewise, the Linux alternative to Win32 is X11. Note that you need both system and rendering APIs if you take this route.
I don't recommend touching Win32 or X11 unless you're extremely serious about some kind of hardcore game engine, which is about the worst decision you could make. Generally, I'd recommend SFML or SDL, as they abstract windowing and system-level details so you don't have to worry about them, as well as simple 2D rendering stuff. They both also expose OpenGL for when you need to do some kind of heavy-handed 3D or post-processing stuff as well.
I'm not sure of the state of OpenGL on Windows. I think you need to get the headers, which should be all you need. There's a good chance that libraries like SFML will either come with that or tell you how to get them.