How to 301 redirect non-www to www url

[eluser]senz[/eluser]
Hi all,
I want to redirect my website from non-www to www url and i got some code like this :

RewriteCond %{HTTP_HOST} ^yoursite.com$
RewriteRule ^(/)?(.*) http://www.yoursite.com/$2 [R=301,L]


I had change my htaccess file with adding that code, but when i write the address : mysite.com, the redirect is going fine and be like this : www.mysite.com. And when i click some page : www.mysite.com/about, my website is going like this : www.mysite.com/index.php/about.

My question is, how to remove "index.php" from the address of my website and i had change the existing configuration in config.php file ($config['index_page'] = "index.php";) to be ($config['index_page'] = ""


Thanks,
Senz