On our 2003 server I ran ADPREP from 2008 32bit with no issues and success at the end, Ran ADPREP /forestPrep, Ran ADPREP /domainPrep.
Running DCPROMO on 2008 R2,
-add DC to existing
-picked our doamin (forest root domain)
Then I am getting the famous message "To install a domain controller into this active directory forest you must first prepare the forest using ' adprep /forestprep. the adprep utility available on the windows server r2 installation media in the support\adprep \ folder."
objectVerison 44 is what returns after running dsquery