var dateToday = new Date();
var Year = dateToday.getYear();
var Month = dateToday.getMonth();
var Day = dateToday.getDate();

// initialize empty array
var imageLibrary = new Array();
// pre-cache four images
imageLibrary["image1"] = new Image(240,180);
imageLibrary["image1"].src = "gfx/001.jpg";
imageLibrary["image2"] = new Image(240,180);
imageLibrary["image2"].src = "gfx/002.jpg";
imageLibrary["image3"] = new Image(240,180);
imageLibrary["image3"].src = "gfx/003.jpg";
imageLibrary["image4"] = new Image(240,180);
imageLibrary["image4"].src = "gfx/004.jpg";
// load an image chosen from select list
function loadCached(list) {
var img = list.options[list.selectedIndex].value;

document.thumbnail.src = imageLibrary[img].src;
}