Dreamweaver & PHP in different browsers -- newbie question

[antena]

hello...

I have laid out several sites in HTML using Dreamweaver MX (OS X user here).  A friend asked me to make a few updates to his site, which uses PHP. 

Anyway, I made the changes (just some of the rotating art that appears on a couple of pages... even used the same filenames as previously), and while the site looks great in Safari, Camino, and Firefox, the modules don't line up when using IE (either platform).

Any ideas as to why this might be happening?  I have a feeling there's a bit of code out of place somewhere, but I'm struggling as where to look.  Here are the pages in question:

http://www.runchicago.com/home/index.php

http://www.runchicago.com/gear/index.php

Thanks for taking a look and any help you might be able to offer.

John