I used the code and stylesheet from your online link which is different from what you posted.
The only difference I can see between IE7 and Firefox is that Firefox shows the footer .botnav over on the right when IE7 shows it central.
You have <div class="content"> above .botnav which is affecting it. Delete the content div and one of the div closing tags:-
............ </p>
</div>
<!-- InstanceEndEditable -->
<!--<div class="content">
</div>-->
</div>
<div class="botnav">
<div align="center"><a href="index.html">Home</a><a
href="activities.html"> Activites </a><a href="contact.html">Contact
</a><a href="links.html">Links </a><a
href="gallery.html">Gallery</a><a href="packages.html"> Packages
</a><a href="map.html">Map </a><a href="wildlife.html">Wildlife</a>
</div>
</div>
</div>
</body>
<!-- InstanceEnd --></html>
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.