The England squad announced by Fabio Capello today isn't the most talented there has been. However they do have one advantage that previous squads have not had- they are about the right age to win the thing. The average age is between 28 & 29 which is about typical for world cup winning squads. Typical England squads have been around 25 or 26 in the past which is far younger than any team that has won the tournament. This squad's age is illustrated by the fact that the youngest player is Aaron Lennon- who was only the 2nd youngest player four years ago.
The common mistake is to overrate the value of potential- the element of surprise- and underrate the importance of proven players who talents and limits are already known. This applies in other sports as well- during the Rugby World Cup I was always sceptical of New Zealand's chances, even though they were overwhelming favourites, because of their young age meant that they would be unused to a high pressure situation. I feel the same about Spain's chances in this tournament, their squad is about 25.