This piece in the Economist points out that there is now a movement to use Moore's law to save money rather than add-on new bells and whistles to computers. I've always thought that it was kind of a racket that computers never got much cheaper, they just got more powerful and stayed around the same price. "Net books" seem to counteract that trend.
I just put Ubuntu on a six year old laptop, whose performance in Windows XP (loaded up with virus protection and who knows what other add ons and spyware) had slowed to a crawl. It works great now.