As I've said many times before. If you got the players for it, go for 3-5-2 with one DMF, two SMF, one CMF and a AMF. Three CB's and a SS and CF.
Most of your midfielders seem to be central ones (who can play at the sides, but are best in the middle). With the players listed I'd go for the following:
Middle CB: Nesta
Side CBs: Jankulovski and Zambrotta
DMF: Pirlo
CMF: Mouthinho
AMF: Kaka
SMFs: Get some if you don't already got, preferably fast ones with good passing.
SS: Aguero
CF: Ronaldo
Edit: If you don't got many SMFs you can always put Seedorf as CMF and use Mouthinho as a SMF