It looks like there is no line break after your headers. In your code:

Code:
<div class="wrapperAttribsOptions">
<h4 class="optionName back">Operating System</h4>
(((you need to break here)))
<div class="back">
<input type="radio" name="id[2]" value="1" checked="checked" id="attrib-2-1" /><label class="attribsRadioButton one" for="attrib-2-1"><img src="images/attributes/msxp01_on.gif" alt="" width="50" height="35" />  Windows XP Home</label><br />
<input type="radio" name="id[2]" value="2" id="attrib-2-2" /><label class="attribsRadioButton one" for="attrib-2-2">Windows XP Professional (+$49.00) </label><br />

</div>
<br class="clearBoth" />
</div>
You can style everything there but I would do something along the lines of...

.wrapperAttribsOptions back {clear:both;}

or...

div.back {clear:both;}

Try adding those to the stylesheet and that should make it so those blocks don't nestle up next to the headers.

Good luck, Jonah