I am trying to hide some content when a radio button is changed. I have been searching the internet for this, but the only thing I found that is close to what I wanted was done in .asp. I tried to convert it, but seeing I do not know Javascript very well, I was unsuccessful. I'm hoping someone here can help me set it right.

Code:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

<head>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type" />
<title>Untitled 1</title>

<script language="javascript">
  window.onload=function(){
     var rb = document.getElementsById('opt0');
     var d = document.getElementById('dvArea');
     if (rb.checked == true) {

                d.style.visibility = "visible";
            }
            else {
                d.style.visibility = "hidden";
            }   
  };
    </script>
</head>

<body>
<form id="frmOptions">
  <input type="radio" name="options" id="opt0" checked="checked" />
  <label for="opt0">Option 1</label>
  <input type="radio" name="options" id="opt1" />
  <label for="opt1">Option 2</label>
</form>  
<div id="dvArea">
     Some contents
</div>
</body>

</html