Domainprep for Exchange 2000

I am installing Exchange for the first time. this is new to me. I installed it on a Windows 2000 server with the latest SP and security patches. It’s on a AD and is a single small domain. I have not ran Domainprep yet and I understand that part of the installation would have ran Domainprep for me already. Am I right ? how do I check if Domainprep has been ran. I believe that it would be obvious when I try to setup the mailboxes ? what affects will Domainprep have on my network ? in other words will it affect my users since I’m training myself here and my users are on the network? also this 2000 server is not being used for anything else on the network. Any help would be appriciated
Thanks