It could be just that IE7 and Firefox give different default top margins to <p> tags.
You can make them both the same by adding margin-top: 15px to the footer <p> tag:-
<p style="margin-top: 15px;" align="center"><span
class="style2"> <a href="contact.php"> Contact Us</a> | .....
You have given the tag a class="style2" but this doesn't appear in main.css so that is having no effect.
I also note that the html source file as I see it has lots of repeating sections of Doctype, html tags and head section and lots of closing tags. This may be because you are using PHP and perhaps you have repeated these sections in the .inc files. The included sections only need the code to be inserted by the PHP tags. It doesn't seem to have done any harm though.
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.