FWIW I just beat the Colts with the Bills on my way to winning SB39 (T.MaGee MVP) and this is how I did it.
Play the Nickel on running downs- As I'm sure you are aware, Manning will pass, pass, pass. Having an extra DB will enhance your coverage. If they run Edge, let him get his yards (within reason) because they will go back to the pass eventually because thats their game.
Use the Blitz judiciously- As evidenced last Sunday @ the Pack, you blitz Manning a lot-you lose. QB trap is a safe zoneblitz to use.
The idea is to prevent the big play so use plenty of Cover 2 and Cover 4 on 3rd and long.
Ball control- run the playclock down to 1 or 2 sec especially with the lead.
Dont panic- If they go up early, relax. You are facing the Colts defense not the 85 Bears. Run the ball, pick your spots, chew the clock, and most of all- when your are in the redzone score TD's
Good luck