Compare user entered password with AD

From: Mike Moore (MikeMoore_at_discussions.microsoft.com)
Date: 07/27/04 

Date: Tue, 27 Jul 2004 10:15:40 -0700

I would like to get the password that a user enters in a textbox of an asp.net web page and compare it in AD. Is this possible? If so, how could I do this in code and what permissions are required?