OK computer. U.S. consumers are being cheated out of the chance to buy the greenest possible computers, according to the Silicon Valley Toxics Coalition and other environmental groups that have joined forces on the Computer TakeBack Campaign. The campaign's latest report card examined 28 computer manufacturers' practices regarding hazardous materials, worker health and safety, and systems for taking back used products. CTBC found that fewer relatively eco-friendly computers are offered for sale in the U.S. than in countries with stronger environmental regulations, such as Japan and European Union nations, which have worked to eliminate hazardous materials from electronics and required …