<SCRIPT LANGUAGE="JavaScript">
var pwin = external.menuArguments;
var str = new String(pwin.document.selection.createRange().text);
pwin.open("
http://www.google.com/search?q="+str+"&hl=ja&lr=lang_ja");
</SCRIPT>
などを
<SCRIPT LANGUAGE="JavaScript">
var pwin = external.menuArguments;
var str = new String(pwin.document.selection.createRange().text);
var url = "
http://www.google.com/search?q="+str+"&hl=ja&lr=lang_ja";
</SCRIPT>
<SCRIPT language="VBScript">
Dim WshShell, objDic
Set WshShell = CreateObject("WScript.Shell")
WshShell.Run Chr(34) & "C:\Program Files\TaBrowser.exe" & Chr(34) & " " & Chr(34) & url & Chr(34), 1
</SCRIPT>
にする