function initializeMaps() {
	
	document.mapPreload = new Array();
	$('map').select('a').each( function(link) {
			var imgTag = link.select('img').first();
			var underImgName = imgTag.src;
			var overImgName = underImgName.replace('under', 'over');
			idx = document.mapPreload.length;
			document.mapPreload[idx] = new Image();
			document.mapPreload[idx].src = overImgName;
		
			link.observe('mouseover', function(e) { imgTag.src = overImgName});			 
			link.observe('mouseout', function(e) { imgTag.src = underImgName});
	});
	
}

Event.observe(window, 'load', initializeMaps);