Over at Everything Sysadmin, there is an interesting discussion of laptop economics.
However laptops are different. Laptops seem to be treated like crap by even the daintiest of users. People drop them, slam them, toss them into the trunk of the car before speeding off bouncing it around. That’s a lot of wear-and-tear. Even if you have a fancy carrying case, there can never be enough padding in my opinion.