I also have a Thinkpad Edge, the cheap Thinkpad line. The build and the quality feel very cheap, but just as you, I've had it for 3 years, I've abused it as my work laptop for 2 years and had no problems with it.
Exactly my thought, the build quality (plastic, stain resistance, etc) and screen resolution are on the cheap side, however if you're like me and you don't care about that sort of things (in favor of something affordable and "just works") I really suggest some ideapads.