How can I add a new PDC as the old domain's controller?

Dear All,
I have a new windows server 2003, and I want it to be another PDC in the domain. And it has a new domain and wants to cover the old domain. The question is how can I add the old domain to the new PDC? a.k.a. One PDC has 2 domains.
Thanks for your answering.

a.k.a. <---請問這是啥東西？:|||:

One PDC has 2 domains ===> Virtual PC or VMware！

[QUOTE=nyker]a.k.a. <---請問這是啥東西？:|||:[/QUOTE]
also known as -> 又名,亦稱

Thank you. That's what I think. I used VMWARE to run different OSs, and I also can simulate the simple network in the domain.