New Orleans' Preservation Hall Jazz Band has been going strong for over 25 years. With their historical name (Preservation Hall itself has been around since 1750!), and instrumentation (usually a variation of trumpet, trombones, clarinet, banjo, piano, drums) you might think they are preservers of the "Dixieland" jazz tradition. But they are careful to say that they don't play Dixieland, instead, what they call New Orleans jazz. It's a bit slower, more bluesy, they explain, with a clear melody and lots of collective improvisation. Whatever you want to call it, the music's good and the musicians are masters. This is bedrock stuff--"St. James Infirmary," "When the Saints Go Marchin' In," and other classics performed to make Louis Armstrong proud. 8 p.m. Tickets are $25, $12 for students. For more information, call 684-4444 or visit the Duke University Institute of the Arts at www.duke.edu/web/dia.