IIS and PHP with $HTTP_SERVER_VARS

Hi The problem I am having is as follows: I setup PHP with IIS and it seems to work fine. I am creating a Intranet site and would like to obtain the user logged on to the networks username. I have setup basic auth but when I visit the site it asks me for my username and password before I can get in. Integrated Windows Auth is turned off. When I turn it on and try to login it says login failed. I know that ASP can have a script added to the page to turn pass through auth but I need one for PHP. I am using $HTTP_SERVER_VARS["LOGON_USER"] to get the username and it works when I login. I just need to get rid of the login box. Thanks for your help in advance. Shaun Garriock *** The contents of this message are confidential and are intended for the addressee only. The views expressed in this message do not necessarily represent those of Robert Gordon's College. Electronic mail transmission is not guaranteed to be secure, therefore, Robert Gordon's College does not accept liability for the contents of this transmission. This message does not form a legal binding contract. ***