Why not end this harrowing year with the mellowest music available? That would be the soft acoustic sounds of Windham Hill which was started in 1976 and is being performed Saturday December 21 at 3 & 7 at the elegant Carriage House in the splendid architecture of the Montalvo Arts Center in Saratoga. Piano, guitar, violin and cello. Mmmm. $50-60.