Permalinks and jquery Error

Hello,
I need help with reloading some part of page, actualy i want to make reload some content (post) on my wordpress blog without reloading page.. simple users can click on refresh button and get new post …

Im make random.php file and im include in my page this file, so there is 6 random posts…
<?php include ‘random.php’;?>
So now i need reload this part on click without reloading all page, im try found solution on the google but cant find any good tutorial or

My code:

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.5.2/jquery.min.js" ></script>

<script type="text/javascript" >
var $j = jQuery.noConflict();
function ajaxs_request() {
$.get('random.php', function(data) {
$('#random').html((data));
});
}
</script>

<div id="random"><?php include 'random.php';?></div>

So all this works very fine if i have Permalinks on Default (http://localhost/wordpress/?p=123)

But when i change Permalink script cant load random.php files, im try change extension to random.html and works but i need to load php..

So where can be problems.. im also try on localhost without any plugins and same…