What would be the proper procedure for making the switch from VM to NT?

The NT listserv is already operational and I've prepared the VM lists
for migration. I FTP'ed one list per the instructions and received several
errors (commands that are oboselte, etc...) That was part of the preparation
phase, changing those commands to be compatible with 1.8c

Other than informing the users of the change, what else should be done
to insure a seamless transition? I'd rather not point the VM Listserver
to the NT Listserver if at all possible. I have a big mess on VM with
one of our deleted lists being used by a spammer program (kaboom).

Thanks for any/all comments, suggestions, experiences, etc...