psql/libpq under mswin

Hi,

I'm hoping someone can point out what I missed here. I'm hoping to get
postgresql to interface with a C++ program compiled under vc++ 6.0 on a
win2k machine.

I have: cygwin 1.3.22-1
cygipc 1.14-1
postgresql 7.3.3-1

Under cygwin, everything seems to run as expected, i.e. I can follow the
steps to create and then use psql to view a db. I built the libpq portion
under mswin (vc++ 6.0) as described in Chapter 2 of the docs, which also
built a version of psql. Attempting to use this version of psql (or libpq)
returns the error:

could not create socket: Address family not supported (0x0000273F/10047)

Can someone point out where I erred?

Thanks,
Bruce