Transition from 2003dc to 2008r2

Bit of an old subject i guess. But i'm performing a transition from a 2003 Domain Controller to a 2008R2 DC. I am planning on bringing the new dc up alongside the old and doing the transition of FSMOs (schema and Dom name master) + roles etc.  What i need to know, is the best practice for transferring the old DC's name and IP address over to the new at the end of the process.  

Should I:
1 bring up the new server using a new IP address and server name.
2: do the transitions.
3: decommission the old server.
4: give the new server, the name and IP address of the old one?

Extra Detail:

We have 2 DC's/

The 2003 one to be replaced: RootDC1 -
IP- 10.16.46.51
Subnet mask: 255.255.255.128
Default G: 10.16.46.1
Pref DNS:10.16.46.51
Alt DNS: 10.16.46.52

A 2008R2 Virtual machine: RootDC2 -
IP- 10.16.46.52
Subnet mask: 255.255.255.128
Default G: 10.16.46.1
Pref DNS:10.16.46.51
Alt DNS: 127.0.0.1

The VM 2008R2 server I am raising: Rootdc (will replace rootdc1)

Proposed During transition            /    Proposed After 2003 decomission

IP- 10.16.46.21                               /   IP 10.16.46.51
Subnet mask: 255.255.255.128      /  Subnet: 255.255.255.128
Default G: 10.16.46.1                     /  Default: 10.16.46.1
Pref DNS:10.16.46.51                     /  Pref DNS: 10.16.46.51
Alt DNS: 10.16.46.52                      /  Alt DNS: 10.16.46.52

And can i just change the name from Rootdc over to RootDC1 without ill effects?

P.s my first time using Experts Exchange, so thanks all in advance!