If you store your DNS without AD it is listed in a folder in the Windows folder so you could probably edit it manually. A quick google should tell you where. I know when I needed to migrate DNS for about 80 domains I was able to copy the dir over to a new server and bounce the dns services and all was well.
If your AD based (I think your not) theres 2 registry areas: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\DNS\Zones HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\DNS Server\Zones ~ Upgrade to Next Generation Antispam/Antivirus with Ninja! ~ ~ <http://www.sunbelt-software.com/SunbeltMessagingNinja.cfm> ~
