Migrating from exchange 5.5 to exchange 2003

I have a client that experienced an exchange server crash. The exchange 5.5 message stores were recovered by a data recovery company. They installed Windows 2003 and Exchange 2003 created a new company. Is there any way to stand up an exchange 5.5 server in a win 2003 native mode domain? Does exchange 5.5 need a NT4 domain controller? Is there a utility to merge the old exchange message store with the new 2003 message store?

Thanks,

Chuck