//Note: userAgent in Opera9.24 WinXP returns: Opera/9.24 (Windows NT 5.1; U; en)
//         userAgent in Opera 8.5 (identified as IE) returns: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1) Opera 8.50 [en]
//         userAgent in Opera 8.5 (identified as Opera) returns: Opera/8.50 (Windows NT 5.1; U) [en]

if (/Opera[\/\s](\d+\.\d+)/.test(navigator.userAgent)){ //test for Opera/x.x or Opera x.x (ignoring remaining decimal places);
 var oprversion=new Number(RegExp.$1) // capture x.x portion and store as a number
 if (oprversion>=10)
  document.write("<script type=\"text/JavaScript\" src=\"script/menu.js\"></script>")
 else if (oprversion>=9)
  document.write("<script type=\"text/JavaScript\" src=\"script/menu.js\"></script>")
 else if (oprversion>=8)
  document.write("<script type=\"text/JavaScript\" src=\"script/menu_opera.js\"></script>")
 else if (oprversion>=7)
  document.write("<script type=\"text/JavaScript\" src=\"script/menu_opera.js\"></script>")
 else
  document.write("<script type=\"text/JavaScript\" src=\"script/menu_opera.js\"></script>")
}
else
 document.write("<script type=\"text/JavaScript\" src=\"script/menu.js\"></script>")