When you migrate a site from Joomla 1.0 or Joomla 1.5 you may have hundreds of pages indexed with Google that will be broken links, showing a 404 Page Not Found error. For SEO, you want to redirect those pages since of having Google remove from the index with your robots.txt. Here is a redirect to catch all of them.
First, make sure you have a .htaccess file in the folder that your Joomla site is in. You may have to rename the default htaccess.txt to .htaccess. Make sure your site still works with it there. There are several tweaks in it that you may need to do before the redirects. For how, to do that, there are many other blog posts on the web.
In your .htaccess, first make sure you have rewrite enabled at the top:
Below that, add this code to redirect the old SEF to the corresponding page on the new site:
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