Windows Server Active Directory

Hi! I have a doubt. I have a Domain hosted on Windows 2003 Server R2. I'd like to add a secod domain controller to avoid any disaster. Which is the recommendation? Is it better if I install a clean Windows 2008 Server an ...

We have delegated our OU's to different AD Security groups. Now the delegation has been so much that its difficult to know who has what rights and where, hence i would like to if there is a way to know what permissions does each group have on different OU in the domain. ...