I have a server environment running W2k3 standard. It consists of 2 domain controllers, ( primary and secondary) and 1 exchange server. We also have a tape drive backup that runs every night. However, seeing as we only have 1 exchange server, if something catastrophic happened, it may take a day or two to rebuild the Exchange server and reload from the tapes. This is unacceptable in my Boss's opinion and i need to figure out a way to have a reliable email server failover so that there is little to no down time. I have considered a server cluster but was told i would need to upgrade to enterprise for starters, and also make sure my servers match the required hardware requirements for a cluter that are quite stringent from what i hear. My question is, what is the best way to accomplish my goal of establishing a secondary email server to successfully limit my downtime?