Does downtime cost you money and lost production? Do you cluster your most critical applications? Do you run a SAN?
With the falling cost of storage a SAN for your servers is now a reality. SAN's with full redundancy have come down in price to the $10,000-$20,000 range. While this is still expensive it does allow for more small and medium size companies to run their applications in high availability mode. You can use Windows built in clustering or virtualization technology like VMware. Even if you are not using HA with VMware you can lock the virtual machine into a spare hosts inventory and still be up and running in minutes, because the storage is on the network.