How to migrate users to new 2000 domain

Now we have a Win2000 domain named “company.com.cn”, and our company want to improvement the communication between all sites, decide to set up a central domain, all sites use child domain.
So we need to set up a new domain named “site1.company.corp”, a child domain of “company.corp”. After it setted, I want to migrate all member servers to the new domain, including Exchange mail server, file server, proxy server, etc. And all users need to migrate to new one.
My question is how to do migration and what should do at client side?