NT Server 4.0 and NT 5.0 or 2K

I have an existing PDC and a BDC in NT 4.0
I just purchased a 2K server. I brought it online taking in consideration that I will be later upgrading the PDC as the root ADS.
So this 2k sever is a member server, which is the DHCP server. It did not move over the user accounts from the PDC. Is it true that I have to create a new set of accounts for people that are going to access it? And what happens when I upgrade the PDC to ADS? Will the existing 2k server’s accounts show up in ADS? I will want one set of accounts that I can mange on one server.