Windows 2003 use Samba user database

Hi, I have been looking for information on how to make a Windows 2003 server use the user database of an existing Samba installation.

What I want is to use the Win3K as a (second) file server allowing users (using Win2K & Win XP computers) to access its shares using their existing user name/password and, of course, maintaining only one user database.

Is this possible at all?

So far I have joined the Windows 2003 computer to the domain controlled by the Samba computer.

However, I cannot connect to any Win3K share using user name/passwords already defined in Samba.

I cannot login to the Win3K via Remote Desktop Connection (I get a message stating that members of the Remote Desktop Users group have this right). So I tried by adding a user from domain to this group (Win3k accepted this) but the result is the same (including the message).

Your help is appreciated.

Juan