Expect Ferrari to raise their game, too, after a shit 2005 season; Schumacher showed that it is, actually, not possible to win grands prix on raw skill alone; you need the machinery. Williams are in dire need of results. The middle of the grid will be strong, with BAR, Sauber, RBR and Toyota all producing competent cars and drivers.
But at the end of the day, Raikkonen is just too good, as long as the team can give him a car that will last the race.