New windows 2003 small business server replacing old windows 2003 server

I have a new windows 2003 small business server and I am replacing a existing windows 2003 server my problem is that the new server install was completed already so the domain is the gerneric domain smallbusiness I am having trouble removing it from the smallbusiness domain and adding it to the domain I already have setup on the old server. My goal is to move over everything to the new server , active directory and everything else ….. any direction will help.

Thanks