HENLEY-ON-KLIP, South Africa >> Mpumi Nobiva was raised by her grandmother in a neighborhood beset by poverty and crime after her mother died of AIDS. Now one of the first to graduate from Oprah Winfrey’s school, she is headed to college in North Carolina. Winfrey spent $40 million to give her girls a campus with computer and science labs, a library and a wellness center. None paid tuition. The st