OpenGL support on different platforms (OpenGL versions)

I’m programming OpenGL with visual C++ 6 which includes the header file for openGL 1.1. My system at home has support for version1.3 (dunno what it is here).
My question is if it would be wise to get myself the 1.3 header file, and use specific 1.3 functionality, or should I stick to 1.1?
Does 1.3 add functionality I MUST have, or is 1.1 sufficient?
Is 1.3 usually supported on older systems (older videocards, drivers) ?
Also on all platforms (Linux, Windows, etc etc)?

In short, is it worth developing in OpenGL 1.3 or is 1.1 usually sufficient for “normal” apps?

To do anything on Windows greater than OpenGL 1.1, you need to treat the functions as you would extensions. That is, you need to use wglGetProcAddress to get an address to the 1.2 or 1.3 function pointers.

So far as older cards, many older cards don’t have very good OpenGL implementations, so you are stuck with 1.1 with those.

You can use glGetString to get the version, as well as any extensions that an implementation supports.

I believe that Sun’s OpenGL is still at version 1.2.3

Just checked Sun’s site. They have a 1.3 beta available.

I am trying to learn to write cross platform OpenGL apps for Sun, Linux, HP, and Windows. I am still new at OpenGL though so I don’t think I have used any functionality above what is supported in 1.1.