Yes, you will be able to access your domain address with or without the "www" in front of the domain name.
When a web site visitor types in "http://www.yourdomain.com" or "http://yourdomain.com" (where yourdomain.com refers to the name of your domain name), they'll be taken to the front page of your site.
You might want to consider changing this however as Google can this as duplicate content and any link value could be split between www. and non www.
Adding the code below into your .htaccess file will redirect to one (whichever one you choose)
RewriteEngine On
RewriteCond %{HTTP_HOST} !^my-domain\.com$ [NC]
RewriteRule ^(.*)$ http://my-domain.com/$1 [R=301,L]