[Aetae]

Например так:

<style type="text/css">
.content div{display:none}
.div1 .div1, .div2 .div2, .div3 .div3 {display:block}
</style>

<div class="content div1">
  <input type="button" value="1" onclick="parentNode.className='content div1'">
  <input type="button" value="2" onclick="parentNode.className='content div2'">
  <input type="button" value="3" onclick="parentNode.className='content div3'">
  <div class="div1">content1</div>
  <div class="div2">content2</div>
  <div class="div3">content3</div>
</div>