window.addEvent('load', function(){
    
    //Attach rollover effects for images whose class is 'hover'
    var oNavImgs = $$('img.hover', 'input.hover');
    
    oNavImgs.each(function(oEl) {
        oEl.addEvents({
			mouseover: function(e) {
				e = new Event(e).stop();
				this.src = this.src.replace('.gif','_over.gif');
			},
			mouseout: function(e) {
				e = new Event(e).stop();
				this.src = this.src.replace('_over.gif','.gif');
			}
		});    
    
    });
});