| Each time you get a new IP, it's still from a range that your ISP predetermined. So if they go after you, they still can track you down through your ISP. So basically, for you, that's the same thing as keeping your static IP up and letting everybody know it's you. Just takes a little bit longer to get caught. The anonymous proxy idea is to get connected to a remote computer, that doesn't keep a log of incoming connections and routes you to a site of your choosing, which then logs the proxy's IP as your own. Using a dynamic IP will just stall an investigation (if there is ever one), not render it useless... | 
