<script type="text/javascript"> 
            before = ""; 
            function testfunc(param){ 
                if(before != "") 
                    document.getElementById(before).style.visibility = "hidden"; 
                document.getElementById(param).style.visibility = "visible"; 
                before = param; 
                } 
        </script> 

<a href="javascript:;" onclick="javascript:testfunc('id1');" ><img src="styles/images/content1.png" alt="Conetnt"></a> 
<a href="javascript:;" onclick="javascript:testfunc('id2');" ><img src="styles/images/content2.png" alt="Content"></a> 
<a href="javascript:;" onclick="javascript:testfunc('id3');" ><img src="styles/images/content3.png" alt="Content"></a> 
<a href="javascript:;" onclick="javascript:testfunc('id4');" ><img src="styles/images/content4.png" alt="Content"></a> 
<a href="javascript:;" onclick="javascript:testfunc('id5');" ><img src="styles/images/content5.png" alt="Content"></a> 
<a href="javascript:;" onclick="javascript:testfunc('id6');" ><img src="styles/images/content6.png" alt="Content"></a> 

<div id="id1" style="visibility:hidden">Content 1</div> 
<div id="id2" style="visibility:hidden">Content 2</div> 
<div id="id3" style="visibility:hidden">Content 3</div> 
<div id="id4" style="visibility:hidden">Content 4</div> 
<div id="id5" style="visibility:hidden">Content 5</div> 
<div id="id6" style="visibility:hidden">Content 6</div>