messina lasalle futures group over at the cme group. still to come an a-list actress takes on a well-known soldier at the box- office...and what impact dvd's are having on studio profits. plus, the implication of 20- dollar a gallon gasoline...we take a ride with one author who thinks it could be good thing. gas prices are well off there highs over $4 a gallon, but drivers are still complaining more and driving less. but what if gas climbed to 6 dollars a gallon, 16 dollars a gallon or even 20 dollars a gallon? what changes would come then? christoper steiner offers his answers in the new book, $20 per gallon: how the inevitable rise in the price of gasoline will change our lives for the better." we followed him around chicago to profile his insights. "as we go from $4 a gallon to $6 a gallon to $8 dollars a gallon each one of those price points will bring a different change. and that's how $20 a gallon the book, is arranged." the world at $4 a gallon is easiest to recognize because well, we've already been there. and as steiner points