Carbonite: affordable unlimited online backup
Prices for online storage are dropping significantly. One good example is Carbonite: a service offered by USD $54.95 per year that allows you to have your entire computer backed up automaticaly, running on the background. Available for Mac and PC, Carbonite also offers "Remote File Access", through which you can recover your file from any computer that has an Internet connection.
Try Carbonite (15 days free trial available) here.