var btn1off, btn1on, btn2off, btn2on, btn3off, btn3on, btn4off, btn4on, btn5off, btn5on;
if (document.images) {
 btn1off = new Image(); btn1off.src = 'img/menu/home_off.gif';
 btn1on = new Image();  btn1on.src = 'img/menu/home_over.gif';
 btn2off = new Image(); btn2off.src = 'img/menu/portraits_off.gif';
 btn2on = new Image();  btn2on.src = 'img/menu/portraits_over.gif';
 btn3off = new Image(); btn3off.src = 'img/menu/photos_off.gif';
 btn3on = new Image();  btn3on.src = 'img/menu/photos_over.gif';
 btn4off = new Image(); btn4off.src = 'img/menu/wallcandy_off.gif';
 btn4on = new Image();  btn4on.src = 'img/menu/wallcandy_over.gif';
 btn5off = new Image(); btn5off.src = 'img/menu/rfq_off.gif';
 btn5on = new Image();  btn5on.src = 'img/menu/rfq_over.gif';
}
function turnOn(imageName) { if (document.images) { document[imageName].src = eval(imageName + 'on.src'); } }
function turnOff(imageName) { if (document.images) { document[imageName].src = eval(imageName + 'off.src'); } }