var rolloverUtil = (function(){
	
	var rollovers = {}; //dictionary of rollovers
	
	function preloadImage( imageURL ) {
		img = new Image();
		img.src = imageURL;
	};
	
	return {
		createRollover: function(imageTag, rolloverURL) {
			preloadImage(rolloverURL); // preload rollover URL
			rollovers[imageTag.id] = {rollover: rolloverURL, rollout: imageTag.src};
			$(imageTag).bind('mouseover', function() { 
				this.src = rollovers[this.id].rollover;
			});
			$(imageTag).bind('mouseout', function() { 
				this.src = rollovers[this.id].rollout;
			});
		}
	}
}());