Just anecdotal, but I had a Thinkpad 600 which lasted from 1998 till 2006. While all machines will fail eventually, it is nice to find the ones which last 8 years instead of 2. Similar to the decision making process for cars: getting one that lasts till 250k miles is generally preferred to one that'll last 50k miles. It would be nice to have a reliability database for laptops similar to that available for cars (http://autos.msn.com/home/reliability_ratings.aspx).
