change domain.LOCAL in domain.com and certificates

Hi!

I've a problem: can you help me?
I've intalled zimbra CS 6.0.5 on a centos 5.4 32bit
During the setup i've specified a mydomain.LOCAL (for internal use and test this system)
After i've added others domains: mydomain.com and mydomain.it

Is this approach wrong? Now the certificates are unusable on internet!
Because of other problems I have now migrated to another machine (Zimbra 6.0.6.1). What procedures do you recommend?
Copy all /opt/zimbra directory to the new machine and then reconfigure it correctly or intall directly lastest version of zimbra and then import users one by one?
How to do it?

thanks to all