See also Your First Domain Controller

http://www.petri.co.il/prepare-for-server-2008-r2-domain-controller.htm

http://technet.microsoft.com/en-us/library/cc753720%28WS.10%29.aspx

Logged in as an admin on an existing domain controller, run:

adprep /forestprep

then, if your existing domain controller is running Windows Server 2003:

adprep /domainprep

You will find adprep on the Windows Server 2008 installation media in the support\adprep folder.

If your existing domain controller is 32-bit, use adprep32.exe.

If you are remote or if you don't have the installation media at hand, you can just download the trial install .iso and use MagicISO Virtual CD/DVD-ROM freeware to mount the ISO file.

http://www.microsoft.com/en-us/server-cloud/windows-server/2008-r2-trial.aspx

http://www.magiciso.com/tutorials/miso-magicdisc-overview.htm

On the new domain controller to be:

Start → Run → dcpromo.exe