function changeImg(imgname,filename) {
		document.images[imgname].src = filename;
		return true;
}

var preloadFlag = false;
function preloadImg(){
	preloadimg = new Array();
	for (i = 0; i < preimages.length; i++) {
		preloadimg[i] = new Image();
		preloadimg[i].src =  preimages[i];
	}
	preloadFlag = true;
}