Running ADPREP /FORESTPREP & DOMAINPREP

My question is: I have 2 WIN2K DM Controllers and I want to add my first 03 Server and run DCPROMO to make it the first 03 DC. I know that you would normally have to run ADPREP /FORESTPREP & DOMAINPREP, but I am already running Exchange 03 on a member server. When I installed that server to make exchange 03 work I had to run ADPREP for both. I am thinking that I don’t need to run it again. Any suggestions…..