The revenge factor only seems to work if you have a better team than the other guy and momentum seems to be the driving factor and the Giants have it big time. The Giants will blow the Patriots out this year if they win the NFC as their front four is even better than the one that won in 2008 and New England is not near as good as they were in 2008. I think if the 49ers are victorious they will win too. The NFC is simply better than the AFC right now and the fact that team like the Giants is doing what they are is simply a testament to that fact as their lower seeds can knock off high quality teams like the Packers and the Saints.
Though the NFC have had their weak spots, the Packers proved it last night. So it goes to show that right now, the best teams ARE the Giants and the Pats.