I watched this talk by a former devout Muslim, a medical doctor and now a follower of Jesus, as it was live-streamed at Georgia Tech University a few short weeks ago. I watched in the company of others, and all of us were impressed with Qureshi's graciousness, and his knowledge of both Christianity and Islam.
Update 11/19/13: Nabeel Qureshi tell his story here: "An Intellectual and Spiritual Journey from Islam to Christianity." http://answering-islam.org/Authors/Qureshi/testimony.htm
Additional posts of possible interest: