Domain controller rebuild

I recently had my primary domain controller crash. The operating system was Windows Server 2000. My secondary controller which is also Server 2000 has taken over. I upgraded my primary controller to Server 2003 Enterprise edition after rebuilding it. How do I get it back into the domain and return it to it’s role as primary domain controller? I have a 4 server domain. Aside from the rebuilt server the other 3 are Windows 2000 server operating systems.