Learn to know how to spot which ones are cheaply made... most laptop motherboards do not fail, but the connectors, sockets, inverters, and cpu fans do. Learn how to keep them clean, change the cmos battery, replace the inverter, upgrade the memory, replace or upgrade the cpu fan.
Avoid the cheap models... where the lcd screen or the inverter goes at an early stage. Be sure the power adapter socket is very solid.
And put everything you can into keeping it cool.
We avoid Sony, Acer, Winbook, eMachines, Compaq, and Alienware. We like Thinkpad, Gateway, Dell Latitudes, some Dell Inspirons, and the HP's in the upper half of the price range.
Put your mental energy where you can make a difference to your friends... fixing the small things on the good ones.