THE DUCK HOLLOW Museum of Art is opening a major new exhibit entitled “Eight Essential Vitamins: The Art of the Cereal Box,” with a special preview for members tonight at 7 p.m. To make room for this groundbreaking permanent installation, the museum had to throw out a lot of outdated rubbish by Turner and Renoir and people like that, so anyone who has some empty wall space over the sofa is welcome to come rummage through the bins in the back hall any time before Wednesday, when the Salvation Army truck comes.