Question: We have a Windows Server 2003 SE server and are moving to a newer, 64-bit system with Exchange 2007. We have made most of the migration, but we are having some difficulty with the DNS. If I turn off the DNS service on the old machine (oldmachine), no one can utilize the DNS - even though the DNS exists on the new machine (newmachine). Any ideas on how to complete this transfer? Thanks.

Did you replace the DNS address on the DHCP server? If the DNS server hold the zone for domain in the AD and you have transfered the roles from the old machine to a new one, the DNS should by available to the network if your workstation point to correct server (the new one).