function ImageRollover(oImg, sReplacementImg)
{
	this.img = Util.Get(oImg);
	
	var oThis = this;
	var sCurrentImg = this.img.src;
	
	Util.AddEvent(this.img, 'mouseover', function() { oThis.img.src = sReplacementImg; } );
	Util.AddEvent(this.img, 'mouseout', function() { oThis.img.src = sCurrentImg; } );
	
	new Image().src = sReplacementImg;	// Preload replacement image
}