Get user's full name rather than domain/user ID..........

Hi,
 Im using : User.Identity.Name
to get the user id of the current user.  This method gives me, for example, domain\fred01.
What I would like to get is the users Full Name eg, Fred Blogs (where Fred Blogs userid is domain\fred01).  Ive been told to lookup Active Directory - but not sure where to start.
 All help appreciated!
 Fiorano
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