Thinking that a computer virus just affects your pc and that you can just restore a backup to get rid of it is not the whole story. You lose time (a day to find your last backup, oh yeah, how do I do a restore again?), lost work since your last backup, lost credibility since you have infected the computers of all your contacts (first target of any virus) and a lost day of production. One day of production is not so bad, right? What if your ‘production’ is dispensing medication or supplies in a hospital, executing payroll for thousands of employees, booking passengers for a flight or preparing customs documents for a shipment of perishable food crossing a boarder. The consequences can be very costly. The prevention? Keep security patch current.