samba - Oct 2005 - UID mapping for Organizational Unit

I am running samba  3.0.10-1.4E on Red Hat using winbind to allow
windows users to authenticate nfs shares. The problem I am having is
with the UID mappings of Active Directory users. When I run the command
"getent passwd" not only am I getting users, I am also getting
computer
objects. This is using all of the allocated idmap uids. I can increase
the number, but I am looking at entries that I don't need to see. Is
there a way to only see certain OUs from Active Directory?

Thanks
Wendell