I was thinking the other night and I'm actually not convinced we will sign a big name midfielder (thinking of Nasri, Modric, Sneijder etc.). Your're right nzmanu, the attacking midfielder spot isn't in Fergie's traditional formation.
Our top line up is potentially going to be something like this:
-------------------------------De Gea---------------------
-----Rafael-------Ferdinand--------Vidic-------Evra---
--------------------Fletcher-----------Carrick---------
-----Valencia-----------------------------------Young--
---------------------------Rooney----------------------
--------------------------Hernandez--------------------
So Rooney plays in the forward playmaking role, with Hernandez ahead of him. Welbeck and Berbatov (if he stays) will offer options up front. Park, Nani (again if he stays), and Cleverley can be added into the three behind Hernandez (and tweak where everyone plays), and Anderson and Giggs offer options in the middle of the park. This is where we are a bit weak still I think, and might need strengthening.
So the options there could be Diarra, Rodwell etc. Obviously Piil Jones has a bit of experience there, and Tunnicliffe and Pogba are coming through. Maybe Ferguson will give these guys a shot instead.
So, in sum, I'm not convinced a big name attacking midfielder will arrive, with the possible exception of Nasri if the Arse don't offer him decent money to stay. But I think there will be one more signing for the middle of the park.