Best way to migrate primary domain?

Hi all,

I am in a situation where I need to migrate my primary domain.  I am not 
losing access to the current primary and I need to maintain a valid mail 
server recieving for it, but I have to change what the primary domain 
for my install is.

AFAICT, there isn't really a way to do it in place and the bast way I 
can find is to through a new installation and then migrate the mailboxes 
over.  Is this the best option I have available to me?

Regards,
Eric