function btnOnGif ( imgName )
       {
	  myImage = new Image;
	  myImage.src = "images/nav/" + imgName + "1.gif";
        document [imgName].src = myImage.src;            
       }

function btnOffGif ( imgName )
       {
	  myImage = new Image;
	  myImage.src = "images/nav/" + imgName + ".gif";
        document [imgName].src = myImage.src;
       }

function btnOnJpg ( imgName )
       {
	  myImage = new Image;
	  myImage.src = "images/nav/" + imgName + "1.jpg";
        document [imgName].src = myImage.src;            
       }

function btnOffJpg ( imgName )
       {
	  myImage = new Image;
	  myImage.src = "images/nav/" + imgName + ".jpg";
        document [imgName].src = myImage.src;
       }