function prepareimg(elm) {
	if (elm.hoveral) return;
	var d=document;
	if (!d.MM_p) d.MM_p = new Array();
	var inum = d.MM_p.length;
	var src = elm.src.replace(/.(\w+)$/,'_o.$1');
	d.MM_p[inum] = new Image;
	d.MM_p[inum].src = src;
	elm.hoveral = 1;
	elm.original = elm.src;
	elm.hover = src;
	elm.onmouseout = function(evt) {this.src = elm.original;};
	elm.onmouseover = function(evt) {this.src = elm.hover;};
}