If someone you know is suffering from a wealth of party theme ideas, a tendency to unnecessarily purchase cocktail dresses, or a habit of saving recipes she's never cooked, she may be an armchair hostess. If you tend to the problem now, she may have a chance at recovery. This awful affliction requires no medication to be cured, and only some light reading therapy. This holiday season, give your plagued friend the answer to her problems: a hostess book. Within days, hours even, you'll see your dear friend off of her lazy chair, actually using those dusty recipe tear-outs, renting dining chairs, and designing party invites with Photoshop. Below are the answers to her problems, which will most likely score you Saturday night plans this winter.