Three reasons why I went for a new one:
1. I saved a huge, huge amount off the list price.
2. Ford Direct (about the only decent source of 2006 cars at the moment) cars were the same or more expensive to buy
3. When they facelifted it right at the end of 2005, they made huge changes to the brake feel and a couple of other small things - so I didn't want to buy a cheaper 2005 car.