If you computer gathering dust in a closet, you're not alone. According to one estimate, Americans will discard about 500 million PCs in the next five years. Computer parts contain lead and other heavy metals. They shouldn't be sent to the landfill or burned in incinerators. Now the industry has taken the first step in setting up a national system to deal with used electronics gear. They plan to impose a disposal charge on sales of new equipment. Minnesota Public Radio's Stephanie Hemphill reports the state of Minnesota has had a leading role in developing the system. {