Customize the user logon screen using Registry in Xp2

Hi there ...
People i m trying to find a way in which i can customize my user logon screen ... i mean i want to change the wallpaper which shows half part in wall paper n half part in the options where u have to select a user (or Admin account) so that you can log on to it .... I hope u fellas understand my question ... And plz plz i m new here ... so if possible can u ppl Mail me the Related Answers to my querry ...

My email add is Lifestealers@gmail.com