I change laptops every 3 - 4 years. I am currently using a Lenovo Ideapad U160 (bought in January 2011) with which I have been extremely happy. Small, light weight and fits into every small bag. It has been running 7 days a week, 18 hours on average. There is nothing wrong with it, except that one plastic piece at the left hinge was broken and cannot be glued together.

Now I am looking for a replacement for work and may use the current one for private stuff at home.