CCNE, net+ many certificate related studies are there.
But there is no substitute for real experience

following books might help u..

Inside Active Directory: A System Administrator's Guide by Sakari Kouti
Active Directory Bible (With CD-ROM) by Curt Simmons
Active Directory, Second Edition by Alistair G. Lowe-Norris
Active Directory for Dummies by Marcia Loughry

keep exploring !!