need a wordpress plugin

Hi, My client has a wordpress article directory website which gets 100s of articles every day by different users. But unfortunately they are are all duplicate articles with same content from different websites. We need you to develop a wordpress plugin which will spin the content and title of each wordpress post and make it unique automatically. This should be done on a continuous process with out any user action. The plugin need not spun the existing articles, but it must spun new articles as soon as a new post has been created. The plugin should have a capability to exclude a category from this activity. Please bid only if you are confident about your wordpress skills and have previous plugin creating experience. Once the plugin is developed, all rights on that plugin to be given to us.. i.e we will become author of that plugin. I'm sorry to say that I can not create any milestone for this project with my previous bitter experience on this similar project.