If you just migrated your entire site to a new platform with a new design it is a LOT easier to change everything over if you just redirect all traffic to the new subdirectory containing your new presence. Try this out for redirecting all visitors to a new wordpress presence:

<IfModule mod_rewrite.c> 
        RewriteEngine On

        RewriteCond %{REQUEST_URI} !^/?admin/ [OR] 
        RewriteCond %{REQUEST_URI} !^/?wordpress/
        RewriteRule ^/?$ /wordpress/ [L]

</IfModule>