I have a cifs joined to AD.
But for unix users i would like to use openldap for windows.
I installed openldap on windows 2003 but it doesn't works, because i don't know how configure the openldap to authenticate the unix users on AD.
Any help is appreciated.
I'm not sure what you mean by openldap on AD. Not familiar with that. But there is a much easier and more integrated way to do this in AD via the Identity Management for UNIX in Windows 2003R2 (or Services for UNIX in WIn2k3 flat).
TR-4073 covers how to configure it in Win2k8 and later, but the same basic functionality applies.
Also TR-3458 covers Win2k3 specifically.
If you're looking for someone to help you set this up step by step, then a forum is not going to be the right place to do that. This is mainly for specific questions about things, such as "I read this doc and set this up, but it's not working because of X."