preload_images = new Array("images/bg_index01.jpg","images/bg_index02.jpg","images/bg_index03.jpg","images/bg_index04.jpg","images/bg_index05.jpg");
preload_obj = new Array("obj01","obj02","obj03","obj04","obj05");

function preloading(){
	for(i=0; i < 5; i++){
		preload_obj[i] = new Image;
		preload_obj[i].src = preload_images[i];
	}
}

$(function () {
preloading();
	for(i=1; i < 6; i++){
		bgSwap('0'+i);
	}
});

function bgSwap(TGT){
	$('#map'+TGT).mouseover(
		function(){
			$('img#bg_index').attr('src','./images/bg_index'+TGT+'.jpg');
		});
	$('#map'+TGT).mouseout(
		function(){
			$('img#bg_index').attr('src','./images/bg_index.jpg');
		});
}