backup exchange server

I have a single w2000 exchange server on a w2000 server for our company. My boss wants to know what we can do as a system redundancy precaution in the event the motherboard blows up. Can we run 2 exchange servers together? Clustering? How can I make it so if our current exchange server blows up people are without mail for the least amount of time without having to wait for the server to be repaired????