You can install Visual Studio 2012 Express which is free and contains the necessary compiler. After that, you have to also install Windows Kits to get the standalone debugger. Alternatively, you can install Windows 7.1 SDK which does not come with IDE but with compilers and debuggers. Windows 7.1 SDK correspond to Visual Studio 2010. But beware, Windows 7.1 SDK has many bugs, and I would not recommend it unless you are targeting Windows XP.
As for MinGW, yes you can also run 32bit programs on 64 bit, but I personally advise you against MinGW. Its integration with Windows is flaky, and its compile speed is far inferior to MSVC's.