I will throw out there Crashplan. You can do online or local or both. Online is nice because it protects you from more than just a HD failure. Although HD failure is prob the most common problem. Theft, fire, flood, lightning strike and power surges often take out the back up drive as well. Crash plan has a deal where you can get up to 5 computers unlimited space for one price. I buy 4 or 5 years of service at a time to get the best price possible. I use it for my computers as well as my parents and inlaws. So far it has been great. I used to use Mozy until they went stupid with their pricing.