Both obtained at a charity softball match in the Chicago, IL area. The major draws that weekend were NASCAR celebs, though other Chicago sports figures were in attendance. The promoters supplied the cards, so there's no clues on there (short of the signature). If it helps to read handwriting, the personalization on the first is for "Mike" (I hope).
So I figured out the second one. It is signed by former NASCAR driver Carlos Contreras, who was the first Mexican born driver in NASCAR. He attended the 2006 charity softball game. Here is a link that matches the signature:
As for the first photo, I didn't have any luck matching any NASCAR drivers from that year or any other year that softball game was held (at least 3 years 2004-2006 from what I can tell). I then looked at the inscription and at first glance it appeared as "To Mike, Go Boxes," which doesn't make any sense, but then I realized it actually says "To Mike, Go Bears." Like you said, this charity game was held in Chicago. During that time Desmond Clark wore #88 for the Bears but the signatures don't really match up. So I'm still not too sure about that one.