promoting Samba to become PDC in windows environment

[Haroon Feroze]

Hi All,
One of our client is planning to migrate his all windows systems to Linux, we are planning to implement Samba as AD replacement. We have planned that first Samba will join existing Windows domain as a member server, and then later on we will remove AD and Samba will become the PDC.
I have tested Samba as a member server, however i am not sure how to promote it to become PDC and how it will handle primary logon query.
I'll appreciate if someone could point me to the right direction.
I am quite new to AD and Samba, thanks in advance for helping me out.
Regards,Haroon Feroze