// rollOverImg
function rollOverImg(imgName, overSrc, bPreload){
	if(!document.images)return false;
	bPreload = bPreload == null ? true : bPreload; //default to true
	this.img = document.images[imgName];
	this.upSrc = this.img.src;
	this.overSrc = overSrc;
	if(bPreload){
		var preloadImg = new Image();
		preloadImg.src = this.overSrc;
	}
	var self = this;
	this.img.onmouseover = function(){
		self.over();
	}
	this.img.onmouseout = function(){
		self.up();
	}
	return(this);
}

rollOverImg.prototype.up = function(){
	this.img.src = this.upSrc;
}

rollOverImg.prototype.over = function(){
	this.img.src = this.overSrc;
}