I think we can definitely beat Arsenal. Their strength is in their front 2 and with Jags and Lescott in great form they can keep them quiet. We do need to be careful about giving away silly free kicks in dangerous areas though as van persie is very good at set pieces.
With Neville, Arteta and Fellaini in the centre we can dominate the midfield and i can definitely see us being more than dangerous from set-pieces with them being unable to cope with the likes of lescott, Cahill and Fellaini in the air.
I can see us struggling big time against Utd though who aren't conceding anything at the back and their tails are up after going back to the top. They also won't sit back like liverpool did after going 1-0 up.