I recently starting work with a company that has gone through multiple sysadmins. I am in the process of cleaning up their network. Currently, I am researching replacing the two AD Controllers (DC1 is a 2003 AD Controller, DC2 is a 2008 AD controller. DC1 is also the primary DNS and DCHP server. I would like to retire these server and replace them with 2012 servers. I would like to keep the IP addresses the same as the current DC1 and DC2 servers, so I don't have to go to each workstation and change the static IP to reflect new DNS servers. I would Like to confirm the roles of the existing servers and make sure they are functioning correctly and move the roles to the new servers. I would also to move DHCP to the new DC2 controller.
Any suggestions, links, horror stories, etc?