I was just at a client the other day and was shocked at how old their servers were. In order to install a new Windows 2008 Dc (domain controller) in the network you need to prep the Active directory Schema to version 44. To do this you will need to run a command line application called ADPREP. ADPREP can be found on the Windows 2008 DVD. Please remember that you will need to run this application on the Windows 2003 machine and NOT the Windows 2008 machine you are trying to create!
You will need to open a command prompt and type this command: adprep /forestprep
Once run you will see something similar. Type “C” and hit enter.
Still in the same command prompt window we will need to update the domain info. We do this by typing: adprep /forestprep
If you get the error above you need to configure the domain to be in Windows 2003 mode.
Re-run the adprep /domainprep command. If successful you will see something like this:
Next run this command: adprep /rodcprep
Run “Dcpromo” from the Windows 2008 server you want to make a DC
Add a domain controller to an existing domain.
Type in domain name and enter credentials
The rest of the items are pretty much NEXT, NEXT, NEXT type questions. At the end of the install you will need to restart the server.