"This document is a step by step guide for configuring Ubuntu
7.10 as a Samba Domain Controller with an LDAP backend (OpenLDAP).
The point is to configure a server that can be comparable, from a
central authentication point of view, to a Windows Server 2003
Domain Controller. The end result will be a server with an LDAP
directory for storing user, group, and computer accounts. A Windows
XP Professional SP2 workstation will be able to join the domain
once properly configured. Please note that you do not have a fully
comparable Windows domain controller at this time. Do not kid
yourself, this guide only gets you a server with LDAP
authentication. Of course this can be expanded to include slave
servers to spread out authentication over multiple networks. Please
also note that it took me approximately two and a half weeks to
compile this information and get it working. The same functionality
can be had in Windows in less than four hours (and this includes
operating system installation). In my humble opinion the open
source community will need to work on this side of Linux in order
for it to be a true alternative to Windows..."