It's really hard to imagine anyone other than Michael Schumacher winning the title again...but I think Williams has the best combo to challenge the Prancing Horse.
Williams has a history of driver combinations that self-destruct a team...and Ferrari has their history of a number one driver, and a number four driver, as well! (Sorry, Rubens.) Barrichello is a great driver, but it's a pity he's MS' teammate.
The last driver to 3-peat the WC was Fangio (who 4-peated!), and that was 45 years ago...MS will probably do it again, but it will be much closer than 2000-01.
Toyota will score 3 points this year, too!