[Samba] Restricting SAMBA access to selected Domain Users?

[Waters]

Hi

I have SAMBA 3.0.14a setup on fedora 3 with windows 2003 Server as PDC.
Currently all the domain users get access to SAMBA from their windows 
clients by giving their domain account information.
I am wondering if I could limit SAMBA access to certain users.

I would really appreciate if you someone could help.

Thanks in advance

Waters