I use msys and mingw for Windows compilation. It's so much easier than Visual Studio --- no messing about with stupid configuration panes and easily scriptable. I also get to use the same makefiles as the Unix port of my program.

The only difficulty is that msys doesn't support parallel make, so builds are fairly slow, but my program's small and I do most of my development on Linux, so I don't care.

(As an additional bonus --- gcc supports C99!)