I see the same problem with IE6 in WordPress 2.5. After applying the IE fix uploading works fine, but then the next bug pops up
While inserting an image from the Media Library by clicking Show (not a very intuitive way of adding images) in IE a fullsize image is shown overlaying the input boxes for size etc,
Firefox works fine, only a small thumbnail is shown and all fields are easy accessible. So it is an IE problem, showing the whole image and overwriting the buttons and input boxes fields.