Q1543 How can I allow a user, after having checked one of radio buttons, and clicked on an image to move onto a dedicated page depending on chosen radio button?

<form>
<input type="radio" name="r1" onClick="window.nextPage='page1.html'"> 1
<input type="radio" name="r1" onClick="window.nextPage='page2.html'"> 2
<input type="radio" name="r1" onClick="window.nextPage='page3.html'"> 3
</form>

<a href="javascript:;" 
onClick="if (window.nextPage)
   window.location.href=window.nextPage; 
return false"><img src="next.gif" border="0" alt="next"></a>