>>Question, though: Is it me or does IE6 implement the box model
>differently/incorrectly as well. I still find myself fiddling with
>padding, margins and widths trying to compensate for differences between
>IE6 and Mozilla. Perhaps it's my CSS coding?
IE6 uses the same correct standards-based box model as Mozilla et al unless
quirks mode is triggered.
Now although your document is XHTML transitional which should make IE6 use
standards mode, you have an xml prolog (<?xml version="1.0"
encoding="iso-8859-1"?> ) which does trip it in to quirks mode. You don't
need the prolog, so just delete it.
see <http://css-discuss.incutio.com/?page=RenderingMode> for more details