WinNT Logons as a $var

I'm using PHP to build our companies Intranet. I am able to setup permissions to certain areas of the website by specifiying permissions to the corresponding folders. In some areas, I need to keep track of who makes what changes where. In order to do this, the person needs to login. Ideally, it would be best to just use their NT logon. It would be extrememly helpful to me if I could get a users NT Logon as a variable in php [maybe as an environment variable?]. I read something somewhere about REMOTE_USER in asp [gag]. Is it possible to get the logon with PHP? Thanks in advance. -Paul Wieland