moving W2K3 to W2K8

hi,
have single W2K3 Std 32bit DC with AD, DNS, DHCP, Group Policies etc on existing local Domain.
Have clean installed W2K8 Std 64bit on ‘new’ local Domain however want AD Users (password) & Computers to be imported on new box.
There’s no trust btw two domains.
Not wanting to add new DC to existing Domain because the current NETBIOS & Domain prefix is not preferred by the owner. Prior to me inheriting the existing W2K3 Server for maintenance, it has come a long way ie: from WinNT 4.0 Server–>performed inplace upgrade to W2K Server–>performed inplace upgrade to W2K3
Intention is to cut-off from old DC and start fresh on new DC & Domain.
Any suggestions/comments much appreciated.

Eddie