ipfailover, redundancy for filmakerserver, mail and web: how

hi, i need for our business a mail/web/filemakerserver running in a datacenter about 600 km away of my office. this server will be the heart of our company, so it must have a real good uptime. is it possible to configure apples xserve that it "knows" that there runs a spare-server which is completely the same? and is it possible, in a troublecase, that the spareserver takes over the complete traffic? or is a loadbalancer needed? or should i buy other hardware than xserve? thanks for your help best regards chris