if (document.images) {
	pic1on = new Image();
	pic1on.src = "images/btn1_r.jpg";  

	pic1off = new Image();
	pic1off.src = "images/btn1.jpg";
	
	pic2on = new Image();
	pic2on.src = "images/btn2_r.jpg";  

	pic2off = new Image();
	pic2off.src = "images/btn2.jpg";
	
	pic3on = new Image();
	pic3on.src = "images/btn3_r.jpg";  

	pic3off = new Image();
	pic3off.src = "images/btn3.jpg";
	
	pic4on = new Image();
	pic4on.src = "images/btn4_r.jpg";  

	pic4off = new Image();
	pic4off.src = "images/btn4.jpg";
}

function turnOn(imgName) {
	if (document.images) {
		imgOn=eval(imgName + "on.src");
		document[imgName].src= imgOn;
	}
 }

function turnOff(imgName) {
	if (document.images) {
		imgOff=eval(imgName + "off.src");
		document[imgName].src= imgOff;
	}
}