I just recently migrated a server 2003 AD and FSMO role to a new 2008 server.
All roles as been transfered. FSMO roles are on the 2008 server. @008 server is the operation master. My issue's are that if I shutdown the 2003 machine no one can log in!
Even the DHCP will not assigned an IP. The 2008 server is the only DHCP on the network.
Right now everybody works with static ip's with their DNS pointing to the 2008 server.