Ok so I have had my main site up for a bit over a year. It is a PR4 for the main page and the blog page is a PR3. I just changed my template and also changed the URL structure of the site as well. So what is indexed in Google now if you click on it goes to a 404 page from my new site becuase that URL does not exist anymore. My question is though when I buld my NEW URL structure for all my blog post will that be considered duplicate content. I am pasting my old blog post under new URLS and the old indexed URLS go to a 404 page? What will happen to my "new site" if I do this?