function rollOver(imageName){
	if (document.Images){
	    var sourceImage = eval(imageName + "_on");
	
	    var targetImage = document.getElementById(imageName);
	    targetImage.src = sourceImage.src;
	}
}

function rollOut(imageName){
	if (document.Images){
    	var sourceImage = eval(imageName + "_off");
	
	    var targetImage = document.getElementById(imageName);
	    targetImage.src = sourceImage.src;
	}
}