var img,
		altimg;

function swapImg(alt)
{
	if (alt)
	{
		document.getElementById("bannerimg").src = altimg;
	}
	else
	{
		document.getElementById("bannerimg").src = img;
	}
}

function prepLink()
{
	img = document.getElementById("bannerimg").src;
	altimg = document.getElementById("altbannerimg").src;
	var elem = document.getElementById("banner");
	elem.onmouseover = function()
	{
		swapImg(true);
	};
	elem.onmouseout = function()
	{
		swapImg(false);
	};
}

addLoadListener(prepLink);