Dear Chris,
Metis is the only library which has to be compiled. I forgot to mention earlier that you will also have to select cmake from cygwin, cmake will be required to compile metis.
For openmpi selection, select the following libraries.
libopenmpi-devel, libopenmpi, libopenmpicxx1, libopenmpif77_1, libopenmpif90_1,
openmpi-debuginfo.
I my case I had downloaded mpich2 from
www.mpich.org/, which also supports mpi interface, and compiled it using cygwin. Subsequently after the compilation of mpich, libmpich.a is created.
However in your case when you have selected openmpi from cygwin, you will have to select /usr/lib/libmpi.dll.a instead of /usr/local/lib/libmpich.a
Both the methods work properly. Don't try to compile mpich2 when openmpi is already installed with cygwin installation.
With Best Regards,
Gourish