Can you please specify the version of Apache and PHP? It seems there is a problem with the pgsql extension in PHP5.2.6 - as Jason Minion had mentioned in another thread, please refer http://bugs.php.net/bug.php?id=44905.
I am using WAMPServer 2 (http://www.wampserver.com/en/index.php) - which provides a good development environment for Windows based Apache - PHP. It allows you to install almost all the existing releases(http://www.wampserver.com/en/add-ons.php) of Apache, PHP (and MySQL) and configure them easily - so that you can enable the MySQL or PgSQL modules as you want in your PHP extensions.
I have PostgreSQL 8.2.4 and WampServer2 (Apache 2.2.6 and PHP 5.2.5) installed on my XP laptop and it works fine. I also use phppgadmin (http://sourceforge.net/projects/phppgadmin) which is similar to but not as much userfriendly (atleast) like phpmyadmin.
Though I have not used myself, I still know that WampServer allows you to install * any number of * latest releases of Apache and PHP and configure and switch between them.
Thanks and Regards,