I have a nagging problem with adding an "add www" rule to my Zen Cart htaccess file. The are some existing rules there for SEO. But I can't seem it to rewrite mydomain.com to www.mydomain.com whilst keeping the functionality of the existing rules.

Here is the current .htaccess file:

#### BOF SSU
Options +FollowSymLinks -MultiViews
RewriteEngine On
# Make sure to change "zencart" to the subfolder you install ZC. If you use root folder, change to: RewriteBase /
RewriteBase /zencart/

# Deny access from .htaccess
RewriteRule ^\.htaccess$ - [F]

RewriteCond %{SCRIPT_FILENAME} !-f
RewriteCond %{SCRIPT_FILENAME} !-d
RewriteRule ^(.*) index.php?/$1 [E=VAR1:$1,QSA,L]
#### EOF SSU

Any help would be much appreciated.

Richard