You're kidding right? Argentina is ranked #1 in the world with a team full of star players. Portugal is ranked #8 in the world with Ronaldo and Pepe and a bunch of no names.
Argentina have Messi, Aguero and a bunch of no names (based on the same comparisons). Most international teams have outright stars compared to the rest but the FIFA ranking means little sometimes. Belgium just are not a better team than most the teams in the top ten (not yet anyway), no idea how they got #2.