redirects with mongrel (dropping the www. from a url)

Hi All,

I have a rails app running on an apache virtual host with mongrel that
i want to set up a redirect from www.myapp.com to myapp.com (dropping
the www.)

I have tried doing this in apache using a rewrite rule (below) which
worked before when the app was written in php.

  Redirect http://www.soccertackle.com/ http://soccertackle.com
  RewriteEngine on
  RewriteCond %{HTTP_HOST} !^soccertackle\.com [NC]
  RewriteCond %{HTTP_HOST} !^$
  RewriteRule ^/(.*) http://soccertackle.com/$1 [L,R]

Now the app has been completely re written in rails using mongrel &
apache (i don't really understand much about web servers but mongrel
set up was nice and simple). However my redirect does not work any
longer. I cant seem to find any information on the web (which would
suggest i'm looking in the wrong places).

can anyone suggest a solution to my problem or point me in the right
direction?
please be gentle, as i mentioned before servers are not my strong
point.

Thank you.