Utd's offence will make short work of our defence, but our offence could do the same to yours, Arsenal are a team that are so inconsistent its impossible to call. Its helped by no Gervinho, Podolski has looked brilliant when Gervinho hasn't played, and terrible when he has, he's not a real winger, he's a striker, and he only shines when there is good interplay and movement between the forward players.
For Germany its him and Klose playing off each other looked brilliant, him and Gomez a tap in artist with no real ability to bring others into a game and Podolski looked rubbish.
One of Podolski's problems is he's been a bit rubbish as the team ridiculously focused on Gervinho for the past 5-6 games, hard to say if he'll come out all guns firing, same for Giroud, will Wenger even play him. It's all a big question, will Wenger got Verm at left back with Kos/Mert in the middle, especially after that performance by Kos which was completely inept.
The main thing this season is most teams have big problems, even the top teams, and every team has a game where they look great and a game where they look inept.
Given everything, I wouldn't expect Arsenal to pull off a good win at Old Trafford, nor Utd to crumble at home, they could go behind but they'll have that home support, strength, mentality to come back.