Exchange 2007 - pixie steps

Exchange 2007 to go live
Needs new 64 bit hardware. This is installed and running and BOY is it quick.
Needs careful planning.
Lots of Macintosh clients running IMAP4 which you can start as a service but you cannot manage through EMS.
Not going to just hit install on Exchange 2007 as it may cause havoc on the network and stop Mac clients connecting.
Need to trial it somewhere such as my home domain.
Separately to that I need a new domain controller to help the GAL lookups. This is also installed and depending on options this may become the HT/CAS as well and leave the MBX role to the other piece of tin.

Both boxes are Windows Server 2003 R2 x64 Edition with service pack 2.

Let's promote one of the new servers to be a domain controller. Start, run, dcpromo. This will fail because "The version of the active directory schema of the source forest is not compatible with the version of Active Directory on this computer". In other words it wants me to run adprep on the infrastructure master.

Now the inf master is a Windows Server 2003 x86 Edition with service pack 2 i.e. 32 bit. The only adprep I have is on the DVD that came with the 64 bit server so the app won't run on the inf master.

You can't move the inf master from the 32 bit server to a 64 bit server unless that 64 bit server is a domain controller. But I haven't got one of those.

I'd scratch my head but the rug is getting bare these days.