Brett Favre is a busted old engine, period. Lot of people are saying that he wants to play today because he is tough and crap, but there is one I haven't heard anybody say: Favre is insane.
Any normal quarterback would sit a game or a few with ankle injuries, but not Favre. Something tells me his wanting to keep his streak alive is some sort of form of "hoarding" and the more games he collects, the happier he is. It's like that crazy lady with 100 cats. With Favre, it's football games. Of course a coach would love to have a reliable quarterback able to throw on any Sunday and Favre has served that purpose for almost 2 decades. But the reason why he was available all those games was because he was healthy and able to move around. Favre has been a lucky mofo. I know he has played through minor injuries, but he is broken down and should rest, or retire again. (And I didn't even mention the whole penis on camera thing.)
So if Brad Childress has any balls, he will start Jackson over Favre at New England and give his team a shot. Favre's injury is also a threat the the Viking's season because they need a healthy quarterback to throw a lot. But Brad is obsessed with Favre and will probably start him and he will collect his 292nd cat, I mean game.