2008 R2 Upgrade

Prep / Prerequisites 

Install Core Servers

Configure Time Server

Time Server

Windows Time

Demote old DC

DHCP

Migrate DHCP from 2003 to 2008 R2

http://blogs.technet.com/b/networking/archive/2008/06/27/steps-to-move-a-dhcp-database-from-a-windows-server-2003-or-2008-to-another-windows-server-2008-machine.aspx

netsh dhcp server export C:\dhcp.txt all

netsh dhcp server import c:\dhcp.txt all 

Rename / IP New DC to old Name