One program which is extremely good with instant failover to another server is
www.doubletake.com. My guess is it is VERY pricey, and it would require your extra server. But, you can have failover servers anywhere including another office or home.
The problem I had was I was trying to get the price and four times I used the live chat feature. I waited over thirty minutes each time, and I never got an operator. It just kept updating and said I was next in line. This doesn't say much for support.
