...
<td>
  <input name="radiobutton" type="radio" 
    onMouseUp="MM_goToURL('parent','agree.asp');
    return document.MM_returnValue" value="radiobutton">
   I agree
</td>
<td>
  <input name="radiobutton" type="radio"
    onMouseUp="MM_goToURL('parent','recent_resultsdisagree.asp');
    return document.MM_returnValue" value="radiobutton">
    I disagree
</td>