I've been using jQuery for years and I have NEVER had a problem like this. Here is the site in question:
http://winterberry.wiremediahosting.com/ jQuery is used all over the site. The recent engagements area on the home page is an AJAX slideshow. There's some jQuery for the login form. On the Case Studies page, jQuery inserts a submenu into the subnav. There are also expanding/collapsing content areas on the About Us/Our Team page and several other pages. The jQuery code works perfectly in FF and not at all in IE7. Code inside $(document).ready calls is simply never executed in IE7.