The organization chart only tells you so much. Here are three articles on the fight for economic policy influence in the Bush Administration.
This August 2002 Washington Post column, available through Brad DeLong's web site, describes the loss of Treasury Department influence in the current administration, and the impact of this loss on the Department - "Treasury Departures Hurt Staff Morale "
This Spring 2003 The International Economy article by Fred Barnes describes the loss of influence by Treasury under Secretary Paul O'Neill, and the efforts by the new Secretary, John Snow, to make up the lost ground: "The Incredible Shrinking U.S. Treasury"
This Fred Barnes article, from the Winter 2003 International Economy plots the interacting trajectories of the Administration's economic policy heavyweights: "The Four Horsemen of Bush Economic Policy" This covers more than the four horsemen of the title, but it is a little dated, important characters have left the administration or changed their positions since the article was published.