Obviously, the game come downs to three things:
1) Green Bay's CB's (in particular, Al Harris and Charles Woodson). The Giants have two legitimate threats in the air. Amani Toomer and Plaxico Buress. Obviously, If the Woodson and Harris can disrupt them enough to falter on their routes, then Eli Manning would have a much harder time trying to pass (Playing man coverage allows them to stack the box, and everyone knows a Manning can't run to save his life). Admittedly, Manning has been playing excellent. He's not 92.9% crazy like Tom Brady, but enough to hush most of his critics. This key because he will go up against a very tough tandem of cornerbacks and a very physical team on defense. They are not afraid to be rough.
2) Giants Pass Rush (Osi and Strahan). Favre isn't the most agile guy anymore either. The Giants pass rush is absolutely imperative now because of the massive amounts of injuries that the Giants Secondary has sustained (Sam Madison, and now Ross?) With Greg Jennings, Donald Driver, Bubba Franks, and James Jones they are going to need to pressure Favre to win. With injured cornerbacks, they must make Favre revert to his winner-take-all, high stakes, INT Prone passing fits he goes through win he forces the ball.
3) Lambeau. Snow + Freezing Temperatures + Eli Manning + On the Road (at Lambeau, no less) + In the Playoffs? ARE YOU JOKING ME? All instincts to anyone who pays attention to football should be going off nonstop! This is like taking the Dolphins to win it all next year.