Fair enough. First, I wouldn't even be posting if Jon hadn't whispered.
OK, I would understand if I said, "To install active directory and create the first domain controller in a new Windows Server 2008 forest, you must keep the following considerations in mind...
You must make forest and domain functional level decisions that determine whether your forest and domain can contain domain controllers ....
But, this is a solution that AMAZING CHARTS put in. You simply put in your username and password unless it also needs the workgroup which I doubt. Part of my suggestions and recommendations are that they are guaranteed NOT to break your network. It is almost impossible to break a workgroup. Domains yes, as you are interacting with Active Directory, using DNS, DHCP, Group policy, Internet Information Services and much more. Not trying to brag about domains, but it is very easy to break DNS or IIS. (Not to completely contradict Sandeep's and my statements about how easy client/server is.
But, I understand. I would be interested in seeing what tech support says.
And, yes, in the hierarchy of server OS, there are forests.
