if (document.images) {            
            img1on = new Image();      
            img1on.src = "/_Image/but1on.gif"; 
            img2on = new Image(); 
            img2on.src = "/_Image/but2on.gif";  
            img3on = new Image();
            img3on.src = "/_Image/but3on.gif";
            img4on = new Image();
            img4on.src = "/_Image/but4on.gif";
			img5on = new Image();
            img5on.src = "/_Image/but5on.gif"

            img1off = new Image(); 
            img1off.src = "/_Image/but1off.gif"; 
            img2off = new Image();          
            img2off.src = "/_Image/but2off.gif"; 
            img3off = new Image();
            img3off.src = "/_Image/but3off.gif";
            img4off = new Image();
            img4off.src = "/_Image/but4off.gif";
			img5off = new Image();
            img5off.src = "/_Image/but5off.gif";
        }


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


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