NEW YORK -- There's a fine line between virgin and vixen, and Victor Alfaro is out to define it. For fall, he's doing it with demure but sophisticated shapes, thigh-high hemlines and unexpectedly sexy fabrics. "It's hard to get delicate with wool," says the designer. "But this one has a crepe-y quality that makes it dressy." For more on New York fall, see pages 4 and 5.