I remember the game where we beat City 1-0 a few years back, Gibson scored. That was January too, albeit towards the end of the month.
Everyone was grouchy because of our form, the place was only about two thirds full - partly because we were crap and partly because the weather was awful.
Jelavic was presented at half time and some Kopite tied himself to a goalpost because the Ryanair CEO supports Man City (honestly).
We went out and hounded them, and despite all the obviously empty seats (probably the most disappointing league crowd in years) the place was properly bouncing - even before the goal.
We loaned Pienaar in that night as well.
My main point is that we kicked on that night, finished the season really well (despite falling apart against the RS at Wembley) and that was definitely the turning point.
If we are all properly up for it we can make an atmosphere like that again, and if the place is rocking like that then I've no doubt we can beat them comfortably.