What is preventing you from using MinGW? That way, you could use the GNU toolchain (Make, GCC, Binutils etc.) and still have full access to the Win32 API. You could reuse almost all of your Unix build scripts, and the rest boils usually down to making your scripts aware of different file extensions (.exe/.dll instead of /.so).
Even better, you can do cross compiling with MinGW. So if your toolchain dosn't perform well on Windows, just use GCC as a cross compiler and build your stuff on a Linux or BSD machine. Then use Windows for testing the executable. (On smaller projects, you usually don't even need Windows for that, since Wine does the job as well.)
(Full disclosure: I'm the maintainer of a Free Software project that makes cross compiling via MinGW very handy: http://mingw-cross-env.nongnu.org/)
Even better, you can do cross compiling with MinGW. So if your toolchain dosn't perform well on Windows, just use GCC as a cross compiler and build your stuff on a Linux or BSD machine. Then use Windows for testing the executable. (On smaller projects, you usually don't even need Windows for that, since Wine does the job as well.)
(Full disclosure: I'm the maintainer of a Free Software project that makes cross compiling via MinGW very handy: http://mingw-cross-env.nongnu.org/)