function newImage(arg)
{
	if (document.images)
	{
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function changeImages()
{
	if (document.images && (preloadFlag == true))
	{
		for (var i=0; i<changeImages.arguments.length; i+=2)
		{
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}
	}
}

var preloadFlag = false;
function preloadImages()
{
	if (document.images)
	{
		a1_over = newImage("../images/a1_over.jpg");
		a2_over = newImage("../images/a2_over.jpg");
		a3_over = newImage("../images/a3_over.jpg");
		a4_over = newImage("../images/a4_over.jpg");
		preloadFlag = true;
	}
}