Neither are the same team that played in week one. The saints are much better and, while still a formidable opponent, the packers are not as good due to injuries. I think the saints win by a TD on a neutral field and in the dome by two. Unfortunately, the only possible match-up must take place at Lambeau and that is a significant advantage for the packers.
There are also three other disadvantages the saints face. 1)They can't rest starters in week 16 because a 2 seed is still a possibility (well, maybe for a half if SF is blowing STL out of the water). 2)Chances are they will still likely have to play in week 1 and 3)If they play in week 1 they have to go on the road to SF for round 2.
If the saints can get though 1-3 above without any injuries then its look out packers even at Lambeau.