After a tough loss to the Bears, the Colts returned home to take on the Vikings.  The Vikes took the lead as Blair Walsh nailed a field goal from 51 yards out for a score of 3-0.  However, the Colts made it 7-3 with Andrew Luck's 3-yard touchdown pass to Dwayne Allen.  The Vikings came within a point as Blair Walsh kicked a 29-yard field goal for a 7-6 score.  However, the Colts moved further ahead as Vinatieri scored a 26-yard field goal, followed by Andrew Luck's 30-yard touchdown pass to Reggie Wayne for leads of 10-6 and then 17-6 at halftime.  In the 3rd quarter, the Colts increased their lead when Vinatieri scored a 45-yard field goal to make the score 20-6.  However, in the fourth quarter the Vikings were able to score 2 straight touchdowns with Christian Ponder's 7-yard pass to Stephen Burton to make the score 20-13 and then a 6-yard pass to Kyle Rudolph to tie the game at 20-20.  With 8 seconds left, the Colts drove down the field and wrapped the game up with Vinatieri 53-yard field goal for a final score of 23-20. With the win, the Colts improved to 1-1 and remain undefeated at home against the Vikings as a franchise.. How many points were the Colts leading by at halftime?