[Samba] Integrating Samba & Active Directory

[Sougat S Ghosh]

I have Linux with 1000 users in /etc/password & another Linux server with
200 users in LDAP. Recently, I have configured an Active Directory on
Windows 2000. I would like to have following:
Whenever users log into the domain, it should find out whether these users
exist in the domain controller and if not, should search both of these
Linux servers and authenticate them. Can someone suggest how to do and
which version of samba should be used.
.
Thanks in advance
Sougat Ghosh