I think if Argentinia does not find some extra 50% they'll have a really hard time. Germanys weakness, counters could he their chance, but not if they play like yesterday. They weren't really trying to play quickly through midfield and break the dutch defense with speed. Messi will be always marked. He'll have two players standing on his feet.
The question will be how the argentinian defense will perform. Yesterday they weren't facing the quick and direct play Germany has shown against Brazil (also before the first goals).
The crowd will probably be on Germanys' side as well. I don't know if that will effect any of the players, but we'll see.
In the end Germany are the big favourite for me.