IE problem with margin, padding, width, who knows?

Recently started helping a non-profit org with their site. I made some modifications and then checked the site in IE 7 on Windows XP and it’s all wonky. The main page is too wide and the menu looks cruddy because of it. I reverted back to their original code that they had before I made any changes and it was already screwy like this… actually worse with one of their graphics being compressed vertically. I’d like to get it fixed for them, but after an hour or so of trying to isolate the issue, I’m thinking it may have to do with this GT Image Chooser plugin… but I’m not sure at all, so I didn’t post it over in the plugin support area.

Anyway, I’m not sure if I’m allowed to offer something up, but I’d be happy to send someone an Amazon gift card as a thank you if you could solve this for me/them.

Here’s the link

Thanks!!