158586 IP cheaters detection system

We need a script that detects cheaters on a website that accept users registration. That means the script detect the user ip and don't let him register another time. Also we need this effective with proxy also, that means if a registered member try to use proxy and register again the script will detect him. We won't the script block all proxies, Intelligent system will take care of all cheaters. We are opened for any suggestions or previous successful systems. Installation of the script included on the project. Description of the system work will be greatly appreciated. good luck,