There's a lot of misleading/frustrating information out there regarding where to find a 32 bit version of ADPrep. Allow me to define the problem: http://www.petri.co.il/windows-server-2008-adprep.htm (excellent info!) states that the Server 2008 DVD is strictly 64 bit and and will not run on a 32 bit server. One must download the 32 bit evaluation version of Server 2008 then extract the \support\adprep folder to some medium that is then mounted on your Win2k (or Win2k3) server and executed.
I didn't want to download a massive ISO and extract files, etc. as I'm on a T1 and time is of the essence. I checked the Server 2k8 DVD's \support\adprep folder and found a adprep32.exe - woohoo! Copy the adprep folder to something that is mountable on your old server, execute adprep32 instead, and feel the joy!
