JYM said:well it doesn't really make any difference at all. If anthing, the www part will not work whereas the original domain will. also, www is a subdomain. If you really want, go to your domain registrar account and set domain.com to forward to www.domain.com
Options +Indexes
Options +FollowSymlinks
RewriteEngine on
RewriteBase /
RewriteCond %{HTTP_HOST} !^www\.domain\.com [NC]
RewriteRule ^(.*)$ http://www.domain.com/$1 [L,R=301]