function openRockCalc()
{
   var win     = null;
   var winName = 'rockCalc';
   var page    = 'http://www.kitco.com/pop_windows/kitcorockcalc.html'; 
   var w       = 600;
   var h       = 460;
   var leftPosition = (screen.width) ? (screen.width-w)/2 : 0;
   var topPosition  = (screen.height) ? (screen.height-h)/2 : 0;

   if(screen.width==800)
   {
      settings = 'height='+h+',width='+w+',top=0,left=0,scrollbars=yes,noresible'
      win      = window.open(page,winName,settings);
   }
   else
   {
      settings = 'height='+h+',width='+w+',top='+topPosition+',left='+leftPosition+',scrollbars=no,noresible'
      win      = window.open(page,winName,settings);
   }
}