Carbonite

If you are a professional service provider, small or even a medium business you can't go without a solution to back-up your data on your PC's so that it is recoverable in case of a hard disk failure, theft, fire, etc. 

After reviewing several Strategy+Solutions likes Carbonite.  It comes with a free 15 day trial and backs up your data on the internet while it works in the background without interruption.  The quality of the service appears to be a very good value considering its price and they claim that the amount of data for back-up is unlimited.