Here are a few links I use for gettings information about Microsoft’s AD and best practices.
Just wanting to share the links with you.
Have fun with them.
Best Practice guide for securing AD installations
Best practice guide for securing AD installations and day to day ops (part 1)
Best practice guide for securing AD installations and day to day ops (part 2)
Windows Server 2003 Deployment Kit: Designing and deploying Directory and Security Services
Server 2003 Security Guide
Server 2008 Security Guide
Achieving autonomy and isolation with forest, domains and OU’s
AD Security Technical Implementation guide (non MS)