In FM07 it was Leicester when I played as Leeds. Which I was pleasantly surprised at as it was usually the case in real life, too.
FM08, it seems to be Newcastle. Playing again as Leeds in Championship, lost in both league matches and the League Cup, back in
Prem, lost to Newcastle 3-1 at home, but same team (albeit slightly slower, shorter passing) beat Man-U 1-0 the next game.
Not sure if it's coincidence or if the players are now programmed to fear a particular team. The first time I played them on this save we capitulated 4-0. Would be impressive if this was intended by SI.