mod.rewrite rule: http://www.site.com to http://www.site.com/folder/ 301
More mod.rewrite examples for your google needs,
google will love you if you use this instead of header/location in php or meta-refresh in html.
Options +FollowSymLinks
RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\..site\.com
RewriteRule ^(.*)$ [L,R=301]