How do I migrate a Windows 2008 Domain Controller to another computer?

Solution 1:

• DC Promo the new server to join the existing domain, wait for al AD data to replicate
• If DNS is installed on the old server, install on the new one. Create an AD integrated zone for your domain DNS data and wait for it to replicate
• Transfer any other roles such as DHCP, WINS etc.
• Transfer all FSMO roles to the new server. (I realise the article is for server 2003 however the process is the same
• Turn of old server and check clients can login and perform all required tasks
• Leave old server turned of but ready for use should a problem occur, for a reasonable period of time, usually a couple of weeks to a month

Solution 2:

Isn't it as simple as adding a second domain controller then transferring all the FSMO roles to the new DC? Not knowing all the details you may have dependant roles than need transferring like dns DHCP etc