function open_product(page,product_id)
{
     pict_width=500;
     pict_height=670;

     url="_product.php?page="+page+"&id="+product_id;

     width=(screen.width/2)-pict_width/2;
     height=(screen.height/2)-pict_height/2-20;
     info="width="+pict_width+",height="+pict_height+",top="+height+",left="+width;
     window.open(url,product_id,info);
}