Show or hide specific divs OnClick of a button (javascript)

Hi

If I have 2 divs on a form how can I show them or not on click of a button. So if I click button 1 I want div 1 (but not div 2) to show, if I click button 2 I want div 2 (but not div 1) to show. Thank you :-)
<form id="form1" runat="server"> <asp:Button id="Button1" runat="server" Text="Button 1" /> <asp:Button id="Button2" runat="server" Text="Button 2" /> <br /> <div id="div1" style="visibility:hidden">This is Div 1</div> <div id="div2" style="visibility:hidden">This is Div 2</div> <br /> <br /> </form>