Since you are running Win2K I would have to assume that your domain is currently AD integrated. If this is the case this will be a simple process.
Join the new computer to the domain. Make sure it has a different static IP from the current DC. You will need to prep your domain for a Win2K3 DC.
http://www.petri.co.il/windows_2003_adprep.htm
Then you can create a replica DC from your current DC.
http://www.petri.co.il/how_to_instal...ndows_2003.htm

If you plan on removing the old Win2K DC, make sure you move the FSMO roles to the new DC and set the new DC as the GC. Also make sure to change the options in DHCP to reflect the new DC. Then you can demote the old DC and remove it from service.

I usually like to wait a week between major domain changes and watch the event logs.