A large number of companies and consumers upgrade to new computers every three or four years and therefore generate an incredible stream of discarded machines. In the U.S. alone, they ditched somewhere between 50 million and 75 million desktops, laptops, and monitors in 2005, according to the Environmental Protection Agency. That amounts to as much as 1.15 million tons of hardwareâ€”or more than 3,000 tons discarded every day. And with sales of new computers growing each year, the waste stream only grows. Though many still work, the majority of these machines end up in landfills.