How can I ensure that my website always opens as www.mysite.com and not mysite.com - this messes up my Google OpenID accounts?

My site has a login using the public id feature. When a user signs up for the first time using their openid, they are redirected to the account creation page. I recently noticed that one user when registering with their google account created an account for the first time. However, when she tried to login again using the same google account, she had to create a new account again. I checked the db and saw that even though it was using the same google account - are the public credentials URLs that were obtained different?

EDIT ===================

Thanks Kobi for the info - the problem is that I need to configure my site to always open with www attached to it i.e. http://www.mysite.com and NOT http://mysite.com

Thanks to this subtle difference, google OpenID recognizes the two urls as different urls !!! help me please

I figured it was htaccess, but I did a little googling and found these htaccess commands:

RewriteCond %{HTTP_HOST} ^site.com [NC]
RewriteRule (.*) http://www.site.com/$1 [L,R=301]

      

        
        
        
      

    

However the problem is that when I use this in my htaccess it does a forward and makes sure the link reads like www.site.com, however it messes up all javascript links - in fact I am using URL rewriting here too .. My whole htaccessfile looks something like this:

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule .* index.php
RewriteRule !\.(js|ico|gif|jpg|png|css)$ index.php 
AddType text/css .css

      

        
        
        
      

    

including those two lines results in url rewriting: (what i am doing here

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I don't think I figured it out :) I put two rewrite lines at the end, thus somehow overriding the other rewrite rules - inserting them into the original fix :) thanks anyway