THE BIG GAMBLE - Lesley Stahl reports on the proliferation of gambling to 38 states and its main attraction, the slot machine, newer versions of which some scientists believe may addict their players. Ira Rosen and Joel Bach are the producers.SILVER OR LEAD - Byron Pitts reports on the murder of the mayor of a Mexican city, where powerful drug gangs seem to be giving authorities a choice of "silver or lead" - join us and we will pay you or don't and we'll kill you. David Schneider and Joyce Gesundheit are the producers.A LIVING FOR THE DEAD - Marilyn Monroe, James Dean and Elvis are dead and so is Michael Jackson. But as Steve Kroft reports, they are very much alive when it comes to earning money for their estates. Frank Devine is the producer.