Windows login using OpenLDAP
Solution 1:
You can do so with Samba 3. Samba 3 can use openldap as a backend. But samba 3 can not mimick an AD. Thus you will logon to a Windows NT domain.
Samba 4 comes with its own LDAP backend but can mimick an AD. Then you would have to sync your users between openldap and Samba 4.
You may also want to take a look at the univention corporate server.