Replace of Windows Server 2003 R2 domain controller with Windows Server 2008 R2

Hi,

Currently my only Windows Server 2003 R2 Domain controller PC had dead and not able to start up. I needed to buy a replacement PC to replace it and i only able to get Windows server 2003 R2 for the replacement PC. What should i do to migrate the whole domain controller from Old PC to this replacement PC and connect it into the network and run it as the domain controller? Thank you.