i've a small office with a single w2k3 sp2 DC(bad idea, but it is real), now, i want to make a clean install of that pc, so, i got another one, install w2k3 sp2, add it to the domain, dcpromo and set it to be a GC, untill now everything is ok, then tried to dcpromo in the primary DC, but it fails with

The box indicating that this domain controller is the last controller for the
domain mydomain.com is unchecked. However, no other Active Directory domain
controllers for that domain can be contacted.  

Do you wish to proceed anyway?  

If you click Yes, any Active Directory changes that have been made on this
domain controller will be lost.

So, i started to move all the roles to the new server as described here, when all was ok with the roles, i tried doing the same, but got the same result. Tried moving the DNS to the new server, but it doesn't make difference. Shutdown to the old server, then tried to log into a workstation, but it fails saying the domain is not available, also coudln't add new workstation to the domain, so i have to power on the old server again.
So, if i successfully move all the roles and dns to the new server:
why dcpromo give such message in the old server?
why if i shutdown the old server the domain is not available??
if i successfully move all the roles and dns to the new server, and i click yes when dcpromo give warning in the old server, will i lose all users, computers, ou, etc.?
am i missing some steps to make this work??

hope you can help me

thanks