Newbiehelp Apache + Active Directory + PHP

I am creating a site and want to use Active Directory users as the login to the site. How do you use PHP to talk with Active Directory to do this login? I have read things about LDAP. Do you have to have that? If so, how do you get that to work? I have to realize that with PHP on Linux. Are there any changes needed on the server (win2k Server) to connect to LDAP.
I have read some tutorials but they didn't help me.

The other thing is, that i can't connect to the LDAP with some other tools like LDAP Explorer or with Visual Basic Scripts

Here is a good tutorial.

http://www.developer.com/lang/php/article.php/3100951

this site even gives you a few scripts to help you test your ldap support

thanks but i need a way to get the password and use it with a form

please read this thread http://forums.devshed.com/t74683/s.html

thanx