Pontiac sticks with a cowboy theme for its Montana minivan in a :30 breaking early in April. Cattlemen, some on horseback and some in minivans, go about their business in the commercial from D'Arcy Masius Benton & Bowles, Troy, Mich., backing the 2000 model. After the cowboys leave the range, a huge set of Olympic rings appears on the ground, an allusion to Montana's U.S. Olympic sponsorship, part of General Motors Corp.'s huge, multiyear deal. Copywriter: Chris McCarthy. Art director: Harriet Hitchcock.