Missing path in pg_config

Hello,

I've installed the PostgreSQL 9.0 binary package for Windows XP 32-bit
and I'm trying to install the temporal extension module available in
pg_Foundry. One problem I can see that I'm running into is that the
path defined for PGXS in pg_config does not exist:

PGXS = c:/program files/PostgreSQL/9.0/lib/pgxs/src/makefiles/pgxs.mk

I have a path up to the ".../lib" but nothing after that. Do I need to
re-install something or run a script to flesh things out?
It seems when I follow the instructions for the temporal module install
(as found here
<http://thoughts.j-davis.com/2010/09/25/exclusion-constraints-are-genera
lized-sql-unique/> ), it bombs out when it tries to find this path while
running make install

Any help greatly appreciated.

Thanks,
John