SERIES PREMIERE: The first two episodes of My Name Is Earl creator Greg Garcia’s new series are presented back-to-back tonight. Watch them both, because it takes two helpings of this new TV treat to begin to comprehend just how ambitious, clever, and entertaining it really is. The Guest Book, like HBO’s new Room 104, is an anthology show in which every episode features a new cast, set in the same rented room. In this case, it’s a rural cabin in a small town, it’s a comedy