I managed to achieve this effect by adding a target attribute to my form. Something like;
<form class="Sharp_Default" id="SimpleLogIn_Sharp_Default" name="SimpleLogIn_Sharp_Default" method="post" action="login.php" target="_parent">
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.