While Vick's actions are completely morally reprehensible, I don't believe that he is a "bad person," so to speak. The problem stems from him being ignorant. Dog fighting is culturally acceptable to some people in the part of the country where he grew up - much the same way cockfighting and bullfighting are glorified in other parts of the world.
It is unfortunate that Vick was unable to turn his successes in sports into a morally improved lifestyle. Although his example is a particulalry viscious and disgusting one, many athletes (in all sports) suffer from a similar problem: they never get their heads screwed on straight.
Unfortunately, I believe that Vick will be considered more of a hero than a villian in prison anyway. I'm sure a lot of people in Southern US prisons are from the same cultures that find dog fighting acceptable. They may take offense to the particulary brutal ways that the dogs were killed, but I don't think he's going to become villified by many convicts. I'm sure he will be the most protected person in that prison - by both guards and inmates.