G++ is not Visual C++ but is the GNU's Not Unix! - the GNU Project and the Free Software Foundation (FSF) C++ compiler. It is available for a wide variety of processors and operating systems. The problem is that it is probably not as easy as you would like it to be to find a built G++ for the Windows environment and install it ready to go without hassle. One important place to look is MinGW -- Minimalist GNU For Windows. Another is Cygwin.
I had found a small (2.8M to download) installation for Windows that is easy to install and use, but now I have lost it.. It is (was) an installation created for university students but great for the rest of us too. It was possible to just download gcc.exe and extract it to a permanent location, but that link is not working, at least not when I checked last . The extracted files need very little installation. The files will all be extracted to subdirectories of a "gcc" directory. Then execute the "Install.exe" program to create shortcuts.
See my Visual C++ Programmer Stuff page for more C++ stuff.