When you use Insert>Page Numbers (assuming that is what you mean by
"plain numbering") Word puts page numbers inside a little frame, which
might cause problems if someone deletes the page number but forgets to
delete the frame (for a description of a possible problem, see: http://word.mvps.org/faqs/formatting/UnaccountablyIndented.htm). On
the other hand, if you use the Insert Page Number button on the
Header/Footer toolbar, no such frame is used, and the page number
field is put directly into the text of the header. While using a frame
for positioning the page number allows for more advanced placement,
this usually isn't necessary.
