Special Characters in Exchange 2K Org

I am installing a new Exchange 2K server in a 5.5 organization. During the install, I was given an error about the name of my existing organization. It has ".net" at the end. I changed the display name and the install succeeded.

When I try to use the Exchange Task Mgr to move a mailbox, it hangs up when it connects to the 5.5 server.

I tried ExMerge and it errored out when it tried to bring up the list of mailboxes on the 5.5 server. The log shows that it is looking for a ".net" Organization that doesn't exist.

Can I change the name of my 5.5 org? Am I doomed?