The cholesterol-wary no longer swallow milk-is-good-for-you ads. Hence the arcane "Got Milk?" campaign. The cream of the crop: a peanut-butter-eating Alexander Hamilton buff who can't articulate Aaron Burr to win a radio quiz 'cause he's got no milk. "That it goes so far afield is what's charming," says adman Jeff Goodby. Directed by Michael Bay (The Rock), the $300,000 spot does the mind good.