Help with htaccess to exclude a folder from redirection

[mesh2005]

I want all requests to all files except cgi-bin to be redirected from non-www to www. I wrote that rule but it redirects all to www, the exclusion is not working:

RewriteEngine On

RewriteCond %{HTTP_HOST} ^mydomain.com [NC]

RewriteCond %{HTTP_HOST} !^mydomain.com/cgi-bin [NC]

RewriteRule (.*) http://www.mydomain.com/$1 [R=301,L,NC]

Please help