Helping to Develop Python
The best place to go for information on how to get involved in core development is http://www.python.org/dev/. It's also good to hang out on the python-dev mailing list, or browse the Sourceforge trackers for interesting items to tackle. The Python Bug Days are also a great way to get involved.
You don't need C programming skills - or any programming skills - to help out. Documentation patches are always helpful. Or if you can code in Python, feel free to help out with the standard library.
Hacking on the C core
For C coders, you really need to be able to build Python from sources. On Unix, that shouldn't be a problem, but Windows users may have problems doing this, as the tools used to build the standard Python binaries (MS Visual C++) are not free.
Free C Compilers for Windows
There are free compilers for Windows. The Cygwin environment offers a full Unix emulation under Windows, including the gcc compiler, and Python is supported on Cygwin. So you could work on Python under Cygwin.
There is a "native" port of gcc for Windows (mingw32), as well. However, although there are patches to allow Python to be built using mingw, these are not part of the main sources, and so are not "official" at the present time.
Also, Microsoft have released the command line tools (compiler, linker, etc) from the Visual Studio product needed to build Python as free downloads. With a little work, these can be used to build a complete, compatible Python binary on Windows. The process is a little involved, so I'll describe it on a separate page - ["Building Python with the free MS C Toolkit"]