Could Favre make the Vikings better?

While nothing is official, there are rumors that the Minnesota Vikings want to talk to quarterback Brett Favre. Nothing has been done and nothing may happen, but it is an interesting thought, could Favre make the Vikings better?
Minnesota has the best running back in football. In two seasons, Adrian Peterson has cemented himself at the top of the league and every defense in the NFL are doing everything possible to stop the Palestine High School graduate. With defenses geared to stop Peterson at all means, that opens up the passing game which is where a Favre could be dangerous.
If Favre could come into Minnesota and not try to be a hero on every play, be a second fiddle to Peterson, then the Viking offense would be very dangerous. With defenses putting seven to eight players in the box to stop Peterson, putting one-on-one coverage on the wide receivers, Favre has the arm and the experience to do some damage, something last year's starter Tavaris Jackson seemed to struggle with a lot.
And if Minnesota can get a passing game going, that would loosen up the defense and give Peterson more running room. We have seen the kind of runs Peterson can have with eight in the box, just image what it would be like with less players crowding the line of scrimmage.
The problem with Favre could be ego. He would have to come into Minnesota and not try to make the big plays all the time but looking at Favre's past, can he really do that? Can he sit back and had the ball of 20 to 25 times and make the throws when need be, or would he try to be that gun slinger who wants to throw it 40 yards down field in double coverage?