No. Most people have dynamic IPs which are allocated on connection, so it's quite possible that my IP today, could be my neighbour's tomorrow. In fact, my ISP doesn't do much in the way of zoning, so my IP today could belong to someone 300 miles away tomorrow. If you go to
http://www.ip-adress.com you can check your own IP address, but the best it can tell you is where your connection pop is. I've just checked mine, and its on the opposite side of the country to where I live.
Another consideration is the ethics of what you are intending to do. If you have a web site which allows people to leave comments, you are inviting those comments. Whether they are good or bad (or even obscene), the place to respond is on the site. These people haven't written to you personally or invaded your privacy, so what gives you the right to invade theirs?