nav_images = new Array("nav_home", "nav_sites", "nav_contact");

function preLoadNavImgs()
{	
	for(var loop = 0; loop < nav_images.length; loop++)
	{
		var new_img = new Image();
		new_img.src = nav_images[loop] + "1.gif";
	}
}

function swap_nav(imgNum, action)
{
	var swapImage = document.getElementById(nav_images[imgNum]);
	swapImage.src = nav_images[imgNum] + action + ".gif";
}