prova con questo codice, ovviamente modifica i path.

Codice PHP:
<html>
    <head>
        <title>prova</title>
        <script type="text/javascript" src="jquery-1.3.1.min.js"></script>
        <style>
            #links
            {
                background:lightgreen;
                width:300px;
            }
            #links a
            {
                margin-right:20px;
                font-weight:bold;
                font-size:30px;        
                color:#000;
            }
            #links a:hover
            {
                color:red;
            }
            #content
            {
                height:300px;
                background:pink;
                margin-top:20px;
            }
        </style>
        <script type="text/javascript">
            function loadContent(elementSelector, sourceUrl)
            {
                $(""+elementSelector+"").load(sourceUrl);
            }
        </script>
    </head>
    <body>
    <div id="links">
        [url="javascript:loadContent('#content','prova1.html');"]Link 1[/url]
        [url="javascript:loadContent('#content','prova2.html');"]Link 2[/url]
    </div>
    <div id="content"></div>
    </body>
</html>