Hallo,
Hallöle!
Ausnahmsweise poste ich mal die Lösung :)
<!doctype html public "-//W3C//DTD HTML 4.01 //EN">
<html>
<head>
<title>Formular beinflussen</title>
<meta name="author" content="fastix">
<meta name="generator" content="Ulli Meybohms HTML EDITOR">
</head>
<body>
<a id="link1" onClick="document.forms['formular1'].test.options[0].value='Test 1'; document.forms['formular1'].test.options[0].innerText='Test 1'">Test 1</a><br>
<a id="link2" onClick="document.forms['formular1'].test.options[1].value='Test 2'; document.forms['formular1'].test.options[0].innerText='Test 2'">Test 2</a><br>
<form action="" method="" target="" name="formular1">
<select name="test">
<option value="Wert 1" id="W1">Wert 1</option>
<option value="Wert 2" id="W2">Wert 2</option>
</select>
</form>
</body>
</html>