The division is the Broncos to lose. Only the Chargers are the team that can threaten the Broncos IMO.
Manning needs to stay healthy and the defense needs to improve of course, which I think is a real possibility.
The Chargers have the 2nd best QB in the division, but their defense has had troubles and Turner seems to have more underachieving type teams than anything else.
The Chiefs have accumulated more talent, but let's face it, they are going nowhere with Cassell at QB. He just isn't the QB that really worried anybody. To win more than 8 games, they will need to win many ugly type games and that is hard to do for a full season.
The Raiders have a rookie head coach, who has never been a head coach at any level. They have many holes and Palmer just isn't very good anymore and they have lost some depth as well.