I'm not sure why people are completely disregarding the Panthers as an opponent late in the season. That team was as good, if not better, than any team in the league in the last few games. That being said...
I think this will be a good game, but I would not be surprised to see either team win handily. While I think the Vikings will come out on top at home (which will be a significant advantage), I am concerned about the pass defense and what Favre might do if the Vikes would get behind early. There's no way he'll go down without a fight, and that could result in a forced pass or two. If the Vikes get down early, I think it will be problematic, as some of the personality issues might get in the way of a comeback game plan.
By the same token, if the Vikes get on top early, or are in the game all the way, I do think the crowd noise will be a factor as far as Romo is concerned. If the game is close, the Vikes have a huge advantage at kicker.
For me, the two key players are the QB's, and how they both respond to negative scenarios if they are faced with them. I don't think the Cowboys will have a lot of success running the football, but I also don't think they'll make it a priority, nor should they (IMO). I think Harvin is a huge weapon in this matchup, and Favre will use him to offset the pass rush, as he will with Taylor and Shiancoe. But I do respect the Cowboys defense, and what they have looked like of late.
I would take Favre over Romo in this scenario at home, but respect Romo of late. I think the RB situation favors the Vikings, mainly due to the Vikes rush defense against the Cowboys. I think the receivers are pretty close if Williams shows up at all, but I do not consider Austin to be better than Rice, and I think Harvin is a more impactful player than Crayton. TE slightly favors the Cowboys, although Favre sure has used Shiancoe plenty in tough games, and he has responded.
Dallas has a substantial edge in the offensive line, and that may help them run the ball some. It will help Romo, too. It will have to, or they will have to keep extra help in to block Allen and Co. (most have been lately), which may affect their passing game plan and routes in a negative way.
Defensive line edge goes to the Vikings. Linebacker advantage goes to the Cowboys ONLY because of the rookie in the middle. I rate Greenway and Leber very highly, otherwise, but have to be realistic. The middle will be very important against the Cowboy offense. Defensive backs advantage goes to the Cowboys by a solid margin, I think. I don't care for the way the Vikes cover people, and think they will give up their usual problem plays.
Other than one game (as I recall), the Vikes special teams have been very good. Kicker and punter are very good, coverage teams are good, and the return games are good. Honestly have not seen the Cowboys return and coverage teams enough to rate them personally. Harvin is a threat, and Longwell is a huge advantage in a game like this.
Point spread leans slightly to the Cowboys, which makes sense to me the way things have played out. I would not bet this game, personally, as I think luck and turnovers will make the difference. If I was going to bet it, I would bet the Vikings, as I think home field is an advantage here. They are 8-0 at home for a reason, and the place will be absolutely on fire this Sunday. I think the Vikings are in a very good mental and physical state right now, and think they will win the game.