One of the options for publishing an InfoPath form to a MOSS Forms Server is as a Content Type. When you publish the form, InfoPath asks for a location to publish it. The Content Type is published to entire site collection. When the form template is published to a forms library, the template and the columns in the content type are added to the form library. The form will automatically update the columns that correspond to the content type. The benefit of using a content type is that you can assign multiple form templates to the same form library.
The problem that we ran across was the location selected for publishing the content type. Even though the content type is published to the entire site collection and can be used anywhere in the site, the users appeared to need Contributor rights to the original published location of the content type. So if you published the content type to the a http://site/subsite then the user would need contributor rights to that sub-site or they would get an “Access Denied” when the form was submitted.
The key is to publish the Content Type to the exact location where you’re going to use it and make sure your users have contributor rights. For us it was a forms library.