C programming language is the only most basic computer language that every programmer should get started with and master. As a common sense, you should know: C language is also the fundamental language of many important programming languages, including Microsoft's C#, Apple's Objective-C, C++ which is widely used in many environments, Linux operating system and its many functions, and so on.
The C language withstood test of time is absolutely not replaceable by its younger brother C++ (it just has not such ability, unless one day the computer does not use 0s and 1s any more). Experienced programmers can use C language to write fast and efficient programs all the time, and even now the running million lines of C codes everywhere fully demonstrate its formidable vitality.
MinGW (formerly mingw32, short for Minimalist GNU for Window) is a minimalist free, open source and the most important, pretty darned good compiler for Windows application development using C/C++.