The Vikings have still not made a decision on who will be the starting quarterback for this weekend’s preseason game against the Steelers.  Tarvaris Jackson suffered a sprained MCL in his right knee in the first quarter of last Saturday’s win over Baltimore.  Coach Brad Childress says a decision on Jackson has not been made.  If he doesn’t play, it is assumed backup Gus Frerotte will get the start.  The Viking host the Steelers at the Metrodome Saturday night.