Installing AD is fairly straightforward and Simon has listed some useful
links for your review.
However, careful planning and design must be taken to consider how the AD
domain will meet your organization's needs. To that end, it is recommended to
consider AD specific MOC classes such as:
Course 2279: Planning, Implementing, and Maintaining a Microsoft Windows
Server 2003 Active Directory Infrastructure (5 days)
and/or
Course 2282: Designing a Microsoft Windows Server 2003 Active Directory and
Network Infrastructure (5 days)
Hope this helps.