If you've been lucky enough to carry Peyton Manning into this final round in the NFL Playoff Challenge, there is no reason to switch him out (even if the other quarterback looks pretty good, too).
While the Saints do have an opportunistic defense, he will likely do a fine job of limiting his errors and making plays in the game. The veteran quarterback should be a lock for 250-plus passing yards and multiple touchdowns.
Austin Collie is a threat to score in any given week, and Dallas Clark is easily the best tight end on the field. At this point, Clark is a must-start in postseason fantasy leagues.
The Saints looked very vulnerable against the run in the NFC title game, so you can start Joseph Addai with confidence. The underrated Colts defense has played the run very well in the postseason and is the better starting option of the two units. Their front seven also has the quickness to corral Reggie Bush and Pierre Thomas, making it difficult to choose a Saints running back to pair with Addai.
If you need to start one of the Saints running backs, side with Bush. He might not post great yardage totals, but he always has the potential to find the end zone.
The Saints' offensive line should hold up well against the Colts defensive ends (especially if Dwight Freeney is limited or out), and Drew Brees will make many key completions even if the Colts do not allow many big plays. If you've had him active already during the NFL Playoff Challenge, it makes sense to keep him active.