function buttonOn(oImage){ 
	imgName = oImage.src;
	imgName = imgName.substring(imgName.lastIndexOf("/"),imgName.lastIndexOf("."));
	imgOn	= "images/" + imgName + "_hover.jpg";
	oImage.src = imgOn; 
	} // end function over_image
	
function buttonOff(oImage){ 
	imgName = oImage.src;
	imgName = imgName.substring(imgName.lastIndexOf("/"),imgName.lastIndexOf("_hover."));
	imgOff	= "images/" + imgName + ".jpg";
	oImage.src = imgOff; 
	} // end function off_image