Dudes, In SharePoint2010 a brand new authentication called "Claim based authentication " has been introduced using which we can provide both windows and form based authentication to a web application.By using this ,you can give individual authentication mode. When you create a sharepoint default web application(SharePoint-80), it willl be classic mode authentication(Windows) itself.You can not extend it to form based authentication in sharepoint foundation2010.For that do one thing.Just delete Shatrepoint-80 web application and recreate the Sharepoint80 web application and don't forget to provide "Claim based authentication".Now you can easily extend the web application to form based web application. thanks Pradeepa If you want some more information regarding Sharepoint 2007 and 2010 configuration and developement please leave your comments here