A native Windows port of the GNU Compiler Collection (GCC)
MinGW: A native Windows port of the GNU Compiler Collection (GCC), with freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All of MinGW's software will execute on the 64bit Windows platforms.
GCC for 32-bit and 64-bit Windows with a real installer & updater
The most recent stable releases from the GCC compiler project, for 32-bit and 64-bit Windows, cleverly disguised with a real installer & updater.
The VSR is a repository of tools and challenges in verification (see for example epubs.cclrc.ac.uk/work-details?w=33971). It is part of the international grand challenge on software verification (eg http://vstte.ethz.ch/pdfs/vstte-hoare-misra.pdf)