Using tables in a Publisher website is a bit tricky and can produce
unpredictable results. It may be because of the way you have it formatted,
but it is hard to say. The basic problem you are encountering is that some
things that work in a print document just doesn't work in html.

From my experience, if you copy the table and then "paste special" it back
as an image (gif is usually preferable to a jpg), it will stay the same
size. You could also do this outside of Publisher in a image editor.

DavidF