Actress Suzanne Pleshette, 63, best known for playing Bob Newhart's TV wife Emily Hartley on the '70s "The Bob Newhart Show," and Tom Poston, 79, who, ironically, appeared on Bob Newhart's '80s follow-up series, "Newhart" (Poston played George Utley), are engaged to be married, Poston has told Variety columnist Army Archerd. They've set May 2001 as the date, says Archerd, who also reports that the Poston-Pleshette holiday card is addressed from "The Post-Ette's."