I am using the "Charity" template, and though it previews fine in Firefox when editing in Dreamweaver, it pulls up without any formatting when you type in the website directly. It works fine in IE. I had this same issue last year and really need a fix. I can't ask people to only use IE to view the site! Any help appreciated.
A simple method would be to make two CSS files. One for IE and one for Firefox and you can tell your visitors that the site is viewable best in IE.
I think if you make another css file for firefox so that the site will also viewable best in firefox.