One new PC requires about 1.8 tons of raw material. Stunning new study from the UN. In particular, chip fabrication takes a tremendous amount of water -- ironic considering that so much of the U.S.'s chip work takes place in low-water areas of the west coast and southwest. Upgrading's a possible path around this -- but PCs (like most consumer devices) are not designed to have much of a life post-retail, let alone to facilitate transformation into something new and better than what it left the factory as.
Architect William McDonough and chemist Michael Braungart are responsible for the best-known call for a new design ethic in the industrial world -- the "cradle to cradle" approach. Should be required reading for anyone fashioning him or herself as a technology-literate person.