writing backend extensions using Visual Studio

Greetings,

I am trying to port a library of backend functions that I've built and
tested on linux to the windows version of postgresql (v8.0.1).

I installed pgSQL on the windows box (win2k) using the binary
installer a while ago and the base installation works fine, so long as
I don't attempt to use my backend functions.

Because the extension functions use a bunch of in-house libraries that
are built with Visual Studio, I really need an approach that works
with MSVC.

After playing around for a while, I managed to get a DLL to build and
work at least far enough that I can CREATE and call the functions from
psql.  However, it looks like every argument I pass into the functions
comes in as null (e.g. PG_ARGISNULL returns true). This clearly is
less than helpful. :-)

Can anyone point me to documentation or example files for how to set
up a project for building extensions functions for postgres on
windows?

Thanks for any help,
-greg