In California's Silicon Valley, the superstars of the high-tech industry are all immigrants: * Pierre Omidyar, born in France, founded eBay * Andrew Grove, born in Hungary, helped start Intel * Sergey Brin, from Russia, co-founded Google Siva Singaram, from India, would like to follow in their footsteps. "Currently I've got an idea for a startup company," says Singaram. "It's in the field of Internet advertising." But because he has no green card, he'll have to return to India to start his company. Singaram and his wife Sangeetha, expecting a baby in May, are here on temporary skilled workers visas....