Checkbox Validation

Hi All

I have got the following code - which is part of a form and what I want it to
do is validate so that the user can only select one of teh boxs - but it isnt
working. If you select one it wont submit the form.

Can some tell me how this should be correctly structured please and end my
misery!

<td class="Form_Headings">Would you like to recieve future email updates?</td>
<td><label><span id="spryEmailUpdates">
<input type="checkbox" name="Email Updates Yes" id="EmailUpdatesYes">
<span class="Typestyle_body">Yes</span><span class="Typestyle_body">
<input name="input" type="checkbox" value="">
No</span> <span class="checkboxRequiredMsg">Please make a
selection.</span></span></label></td>