The only time I thought I lost everything was years ago when I was 19 or 20 yrs old. I remember how stressed I was over the data, but luckily the support technicians managed to save the hard drive (under warranty). Since then I was lucky and always backed up my data on an external hard drive at least once a month.

I do use SugarSync now, paying $5 per month for real-time data protection. It gives me 30 GB of space to play with, and I only use about half of it. Worth the price, especially if my computer freaks out on me right this moment - it would be as easy as a simple download to get all my files back in the shape they were last left in.