1. Backup your databases.
2. shut down the source server.
3. In ADUC, rest the computer account of the source server.
4. Load the OS on the destination server, joining the domain with the same name.
5. service packs, etc.
6. Install exchange on the destination server with the /disasterrecovery switch
7. Service packs, backup agents, antivirus,etc.
8. Restore from tape to the destination server.