How Long Do Laptops Last?

It seems like a lot of people I know have the same computer for 5+ years. This isn't the case for me just because I use it so often. I've owned all different brands in lots of price ranges. Last time I splurged on a Sony Vaio hoping it would last longer. The other cheaper brands seemed to only last for 2 years. I loved the Sony and it never gave me a problem until the day it died (cause of death still unknown). I had it for 2.5 years. I think this time I'll just stick to the middle of the road again and pay for one that will last for just two years and plan on replacing it after that.