From PhP/Linux to WIN2K3 ADS authentication

Is it possible to authenticate to a WIN2K3 PDC from a PhP based webpage running on Linux. Its for a Intranet site. Users should be able to use their AD username/password and use the site, which will be using MySQL database. Any ideas?? In the worst case, I can have the same username/password built into the MySQL database and authenticate with the database but I don't want to do that. It's a hassle.

Thank you,
Sanjay.