Wondering what to do with that old Commodore 64 or Macintosh II gathering dust in your basement? According to an eBay survey, you're not alone -- some 50 percent of American households have unwanted PCs in storage. That's why the online auction giant has launched an electronics recycling program they call Rethink. In a partnership with environmental groups, postal services, and major tech names including IBM, Intel Corp., Apple Computers, and Hewlett-Packard, eBay will serve as a conduit for sales, donations, or recycling of old electronic equipment. Enviros hope the program will reduce the number of gizmos that find their way to the landfill -- currently some 400 million every year -- where they can leak harmful toxins like lead and mercury.