In order to remove index.html or index.htm from urls I use the following in my .htaccess
RewriteCond %{REQUEST_URI} /i
A better solution would be to place the index.html rule ahead of the www rule and inside the index.html rule ADD the www prefix to the destination url. This way someone looking for http://domain.com/index.html would get sent to http://www.domain.com/ by the FIRST rule. The second (www) rule would then only apply if index AND www are missing, which is again only one redirect.