The advice I've replied to is exactly right. In my case, I fly almost every week on business, and I buy my own laptop. By the end of the second year, I almost always experience some type of failure in my laptop--either failure of a component or an accident (liquid into the keyboard). I always buy the all-perils warranty for my laptop and I always come out ahead. I am out at the extreme upper end of the bell curve, and so I benefit at the expense of the insurance company.
One of the benefits of the warranty (on my HP laptop) is that I buy the onsite, next business day service. So, no matter where in the world I am working--and I work in the US, Canada, Europe, and Asia--an HP tech shows up and fixes my laptop without the need for me to visit a service centre or return my laptop to depot by courier. This is part of the business value to me.
However, I do not buy any other extended warranties; because in all the other situations I am not out at the extreme end of the risk curve and so I will always lose.