Try OpenGL. It's portable and very nice. Learn how to use it from here. In my opinion, this is the best book there is to learn OpenGL with...of course, I want to be a game programmer, so of course I think that.
OpenGL has become the standard for graphics, and a good portion of video game developers (probably) use it for graphics routines since it can accomplish more (graphics wise) than DirectX...and it's more portable too.