right havn't tried it with United but never struggled on any FM game i have had, last years FM 08 was most deffintely the hardest game.
Anyway for United make sure you don't play too many flair players you need to even it out. Below i will put the eleven i would play if no transfers, it kind of resembles current team.
----------------------------Van Der Sar---------------------------------
----Brown-------Ferdinand-----------------Vidic--------------Evra-------
-----------------Hargreaves------- -------Carrick------(these are CM not DM)
-----Ronaldo------------------------------------------------------------Nani------- (AM)
-------------------------------Rooney--------------Tevez-----------------------
This is the team I would start with, I would maybe look at buying a new left midfielder which would mean you would have a very good second team or look to change the formation to fit in 3 attacking midfielders and one striker however for game up against the Kosh this isn't the best tactic.
Tell me your squad for city and I will tell you how i would play.
Cheers