function wopen(url, name, w, h)
{
  // Fudge factors for window decoration space.
  // In my tests these work well on all platforms & browsers.
  w += 32;
  h += 96;
  wleft = (screen.width - w) / 2;
  wtop = (screen.height - h) / 2;
  var win = window.open(url,
    name,
    'width=' + w + ', height=' + h + ', ' +
    'left=' + wleft + ', top=' + wtop + ', ' +
    'location=no, menubar=no, ' +
    'status=no, toolbar=no, scrollbars=no, resizable=no');
  // Just in case width and height are ignored
  win.resizeTo(w, h);
  // Just in case left and top are ignored
  win.moveTo(wleft, wtop);
  win.focus();
}

function toggleimage(elm) {
	var elem = document.getElementById(elm);
	var srcstring = elem.src;
	var srcstring2 = srcstring.replace(".jpg", "");
	
	if(srcstring2.search("_2") == -1)
	{
		srcstring2 = srcstring2 + "_2";
	}
	else
	{
		srcstring2 = srcstring2.replace("_2", "");
	}
	elem.src= srcstring2 + ".jpg";
}

function changeamount(n)
{
	if(document.forms[0].elements[n].checked == false)
	{
		temp = document.forms[0].elements[n].value;
		base = document.forms[0].total.value;
		total =  parseFloat(temp) + parseFloat(base);
		document.forms[0].total.value = total.toFixed(2);
		document.forms[0].elements[n].checked = true;
	}
	else
	{
		temp = document.forms[0].elements[n].value;
		base = document.forms[0].total.value;
		total =  parseFloat(base) - parseFloat(temp);
		document.forms[0].total.value = total.toFixed(2);
		document.forms[0].elements[n].checked = false;
	}
}