Did a little research here.
Since 2006 we are 4-0 when favored by a touchdown or more.
Week 14, 2007 - Bills favored vs. Miami by 7 points. (W, 38-17)
Week 3, 2008 - Bills favored vs. Oakland by 10 points. (W, 24-23)
Week 4, 2008 - Bills favored @ St. Louis by 8.5 points. (W, 38-17)
Week 17, 2009 - Bills favored vs. Indianapolis by 8 points. (W, 30-7)