You're mixing double and single quotes all over the place! Try:
<?php
$sql="SELECT CatName FROM Category WHERE FieldID=2";
$query=mysql_query($sql);
$result=mysql_fetch_array($query);
?>
<SELECT Name="Choice" SIZE="1" >
<?php
while ($result = mysql_fetch_array($query)) {
printf('<option value="'.$result['CVTitle'] . '">'.$result['CVTitle'] . '</option>');
}
?>
</SELECT>
Diego