function myChgPic(myPicURL){
   document.images["myBigImage"].src = myPicURL;
}

function Preload() { 
var img = new Array();
for (var e = 0 ; e < 8 ; e++) {
img[e] = new Image();
} 
img[0].src = "img/map_01.jpg";
img[1].src = "img/map_02.jpg";
img[2].src = "img/map_03.jpg";
img[3].src = "img/map_04.jpg";
img[4].src = "img/map_05.jpg";
img[5].src = "img/map_06.jpg";
img[6].src = "img/map_07.jpg";
img[7].src = "img/map_08.jpg";
}

if (window.addEventListener)
window.addEventListener("load", Preload, false)
else if (window.attachEvent)
window.attachEvent("onload", Preload)