If speed isn't an issue you could try Cygwin which comes with gcc which includes a fortran compiler. I mention speed because IMO apps running under cygwin are noticably slower than 'native' ones. And ...
A family of C, C++ and FORTRAN compilers for PCs from Sybase Waterloo, a division of Sybase. Originally produced by Watcom International Corporation, Waterloo, Ontario, Watcom compilers have been ...