I'm not aware of any particular tie-in between Windows 7 and Domain Controller and Samba and OS X Server Open Directory LDAP Services.
Samba did provide limited Domain Controller capabilities and can use Domain Authentication, but the Apple installation from 10.6 is an old release and I've had some problems getting that older stuff to work. You'll likely have to hand-manage Samba to get this to work, by following the directions at the Samba.org web site, too.
The best resource I've encountered for digging around in this topic area is the archives of the Mac Enterprise mailing list.
FWIW, Microsoft has (migrated from? abandoned? deprecated?) Domain Controller authentication in favor of Active Directory some years ago, and Apple has abandoned Samba in more recent releases; this is a dead end. If you are using Windows Server and Active Directory, then OS X Server can be configured in what's called a Magic Triangle configuration; where you have Windows handling Windows authentication, and OS X Server handling OS X authentication, and coordinating across the two. Or (with newer OS X releases) Apple has improved integration with Active Directory.
Thanks for this answer,
i will look around samba.org for more informations about my issue.
For more "understanding", our network have some server, i m talking about one "classroom" wish is the "labo" where studients can use computers for their studies obviously, there is Mac OS x (leopard) and Windows 7 clients. Only the Mac os x 's clients can log on the network. There is no AD architecture...
Maybe in future, we should change the infrastructure and replace Mac os x server by a linux+ldap distribution...
But not for now.