http://seo.ijoomla.com/ Mistake number 3 is not fixing the problem of duplicate content on your Joomla site. What happens with Joomla is that your site actually has 2 versions...read more about this Joomla SEO mistake and others here: http://seo.ijoomla.com/

To process redirects from old www pages to the new, non-www equavalents, add the following code to your .htaccess file:

Rewritecond %{https} = off
RewriteCond %{HTTP_HOST} !^domainname.com$
RewriteRule ^(.*)$ http://domainname.com%{REQUEST_URI} [R=301,L]