Hab ne Lösung gefunden, :o), trotzdem Danke
<SCRIPT LANGUAGE="JavaScript">
var suffix = ".htm"
function go_there() {
objWin = window.open(document.pass_form.url.value + document.pass_form.pass.value + suffix,'rapport');
}
</SCRIPT>
<form name="pass_form" onSubmit="go_there();return false">
<br><input type="text" name="pass" size="20" value="">
<input type="hidden" name="url" size="20" value="http://www.xxx.li/xyz/">
<input type="button" value="OK" onClick="go_there()">
</form>