This post is really for my own use but if you find it useful then great! I use this code to force WWW in my URL’s. It works for me in Joomla and standard XHTML sites. If using it for Joomla you will see RewriteEngine On already in the .htaccess file, just copy the last two lines and put in under RewriteEngine On then save. For everyone else you have to include RewriteEngine On or it doesn’t work.
RewriteEngine On
RewriteCond %{HTTP_HOST} ^yourdomain.com [nc]
RewriteRule ^(.*)$ http://www.yourdomain.com/$1 [R=301,nc]
