I just need to verify with some other experts how the switch to Server 2003 DFL works. I have a mixed mode domain, in 2003 interim mode. I have 2 NT4 domain controllers left, they aren't used anymore, and getting rid of them shouldn't be an issue. My question is what happens when I go to switch the domain function level, will it let me make the switch while the NT4 DCs are still online? Will it just break the replication and functionality of the NT4 DCs, or will the wizard force me to remove the computer accounts from the domain?