preload_image_Nav = new Image();
preload_image_Sub_Nav = new Image();

function preloadRollOverImages()
{
	preload_image_Sub_Nav.src = "_image/topNavBackgroundOver.png";
	preload_image_Sub_Nav.src = "_image/btmNavBackgroundOver.png";
}

function preloadRollOverSubImages()
{
	preload_image_Sub_Nav.src = "_image/overSubNavButton.png";
}

function navRollOver(obj, isOver, rollOverImage)
{
	if (isOver)
		obj.style.backgroundImage="url('_images/" + rollOverImage + "')";
	else
		obj.style.backgroundImage="";
}

function subNavRollOver(isOver, obj)
{		
	if (isOver)
		obj.style.backgroundImage="url('_images/overSubNavButton.png')";
	else
		obj.style.backgroundImage="url('_images/subNavButton.png')";
}