Fargo's primary star to me, beyond the ineffable Frances McDormand, is the score.
Carter Burwell's score during the opening credits still gives me chills. It sounds rural at first, slight and down home, as warm and inviting to the viewer as the snow blasted landscape you're viewing during the credits is not.
Shortly after the credits begin, you see a car driving into the scene from far away, and the music begins to swell into an ominous and dramatic crescendo (which contains the scariest sounding sleigh bells ...) that completely shatters any illusions of quiet rural life for the viewer. The score serves during this sequence to tell you that EVENTS are gonna happen during this film. And the viewer sucks it up.
The Coen Brothers also are playing a very big joke on you with Fargo. They say at the beginning of the movie that the events which are depicted are based on truth. They ain't, except in the most vague of ways. The movie is manipulative, meant to make you view the human condition as tragic and petty, and if the viewer feels that the events up onscreen really happened, then so much the better. The score for the movie feeds right into that ... making you feel all the emotions the Coens want you to feel at the times they want you to feel them.
Only a skilled composer, or perhaps a brash one, could come up with a musical score to equal the manipulation being exerted by Fargo's visual elements. Burwell falls into both categories to me, and he's since become one of my favorite movie score composers as a result. His work illustrates to me how much more fun a movie can be when the music is as much an actor as the actors themselves, and the viewer is willing to let him or herself be taken for a ride.