var visibleDivID = 'mainPicture';

function toggleLayer(divID)
{	
	if (document.layers)
	{
		alert("Here");
		document.layers[visibleDivID].visibility = "hide";
		document.layers[divID].visibility = "show";
	}
	else if (document.getElementById)
	{
		var divToShow = document.getElementById(divID);
		var divToHide = document.getElementById(visibleDivID);
		divToShow.style.visibility = "visible";
		divToHide.style.visibility = "hidden";
	}
	else if (document.all)
	{
		alert("Here");
		document.all[visibleDivID].style.visibility = "hidden";
		document.all[divID].style.visibility = "visible";
	}
	visibleDivID = divID;
}