// preload mouseover pics

NumberImg       = new Array()

for(var i = 0; i < 10; i++)
{
        NumberImg[i]    = new Image()
        NumberImg[i].src        = "detail" + i + ".jpg"
}
 
// show picture

function show_image(idx)
{
        document.showimg.src    = NumberImg[idx].src
}

// hide picture

function hide_image()
{
        document.showimg.src    = NumberImg[0].src
}