NT authentication help

Dear ALL,

I'm working on a win2k, IIS 5.0, PHP and MYSQL system.
I activated Integrated windows authentication using IIS and i was able to popup a login dialog box and could restrict access by authenticating through the NT PDC.

The problem is how can i pass the username (which is a domain user in the NT domain) into a PHP script for further processing.
Since it's not an apache-based system, there is no username/password file stored locally in the web server (i didn't intend to do so since my intention was to utilize ONE set of passwords for NT domain intranet logon and web authentication in my school).

I've tried the variables $REMOTE_USER and
$_SERVER['PHP_AUTH_USER']. It failed and those variables returned NULL strings.

Your suggestion would be mostly appreicated.

regards,

KK Lee