I remember reading about this in 'National Geographic'

But this New York Times slideshow is very, very good at showing what happens to First World's castoff computers when they reach Africa...

http://www.nytimes.com/slideshow/2010/08/04/magazine/20100815-dump.html

PS to the New York Times: Putting an ad in the middle of of slideshow is just tacky and annoying.

(Thanks to @JoelJohnson for re-tweeting the link from @dylan20)

For more, here's that National Geographic piece on hi-tech trash:

http://ngm.nationalgeographic.com/2008/01/high-tech-trash/carroll-text