drupal and ajax (ahah)

Hi all,
hoping someone can help me solving this:

Outside drupal, I wrote a php script - testit.php - that reads the content of a directory and outputs it in an unordered list surrounded by a div.
Then, in the html file I have:

jQuery(document).ready(function() {
    $.post('/files/testit.php', {'p':1}, function(data) {
        $('#sgcontainer').empty().html(data);
    });
});

and it works perfectly. (There is more code to account server side ajax (ahah) pagination...)

Then, in the quick and dirty way, I tried to insert (setting the paths accordingly) the above code in a drupal 6.3 node of type page, but loading the drupal page the php script isn't executed and I get, in the div #sgcontainer, the php code (sort of) listed instead of the resulting html.

The same if I use GET jQuery method instead of POST.

Is there any simple way to get the php script called by jQuery executed on the server without writing a Drupal module ?

Any help appreciated, thank you.