[jQuery] Selecting elements loaded from an AJAX call

[Keighl]

I need some help with jQuery theory. Why can't I select an element
that has been loaded through an AJAX call? For instance, I'll load
table.php that renders like this:

<table>
  <tr>
    <td>1</td>
    <td><a id="foo">Foo</a></td>
  </tr>
</table>

I make the ajax call to it like this:

$.post(
    "table.php",
    {  },
    function(str) {
        $("tablebox").html(str);
    }
);

But then, when I try to bind and event to one of the elements from the
AJAX call, I get nothing:

$('#foo').click(function() {
      alert('You clicked Foo');
});

I've tried binding the events from within the $.post callback, but
still nothing. Can anyone explain why this is the case, and if there
are any options I'm overlooking?

Thanks!