On the old server:

  • Open a command prompt and run 
    netsh dhcp server export C:\dhcp.txt all
  • Copy c:\dhcp.txt over to the new server

On the new server:

  • Install the DHCP role
  • Open a command prompt and import the dhcp database you exported 
    netsh dhcp server import c:\dhcp.txt all
  • Change the DNS / GW addresses under scope options if necessary.
  • Un-Authorize / Stop the DHCP service on the old server,
  • Authorize / Start DHCP on the new server: Click Start, point to All Programs, point to Administrative Tools, and then click DHCP. Right-click the server object, and then click Authorize (this is kind of a pain, I’ve found that restarting the DHCP server after you authorize it should get it working).