As part of giant U.S. Steel, Marathon Oil was often overshadowed. But since their split two years ago, Houston-based Marathon has come into its own. Net income doubled last year, thanks in part to high energy prices. But Cazalot mostly credits other factors for the strong showing: exploration successes in places like Angola, Norway, and Equatorial Guinea, and improvement in refining, marketing, and transportation operations. Cazalot shed $1.2 billion in assets as part of a sweeping effort to help cut debt--one reason margins grew from 1.9% in 2002 to 2.8% last year.