Borland C++ Compiler: Download it here.

Extracted from the Readme file unzipped after installation:

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1. Run freecommandlinetools.exe; choose the drive and folder into which you want to install the free C++Builder 5 command line tool development system.

2. From the bin directory of your installation:
" a. Add "c:\Borland\Bcc55" to the existing path
b. Create a bcc32.cfg file which will set the compiler options for the Include and Lib paths (-I and -L switches to compiler) by adding these lines:
-I"c:\Borland\Bcc55\include"
-L"c:\Borland\Bcc55\lib"
c. Create an ilink32.cfg file which will set the linker option for the Lib path by adding this line:
-L"c:\Borland\Bcc55\lib"

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GCC for Windows: http://www.mingw.org/mingwfaq.shtml