Add 'class' or 'id' for this anchor.
<?php
if(isset($user) && (isset($pass)) { //whatever u want for this
echo "<td><a href='www.something.com/file.htm' class='memberlink'>Click</a><td>";
} else {
echo "<td>Click</td>";
}
?>
And you can change in css:
a.memberlink {
}
Good luck.