Extracts taken from a document called 'Page layout in LaTeX' - the
fancyhdr user's manual - by Peter Oostrum:
http://tug.ctan.org/cgi-bin/ctanPackageInformation.py?id=fancyhdr
You can set the rule width of the header/footer using the following
commands:
\renewcommand{\headrulewidth}{0.6pt} % 0.6pt header rule width
\renewcommand{\footrulewidth}{0pt} % remove footer rule
The \headrule/\footrule command defines how the rule for the header/
footer is drawn. You could redefine them using (say)
\renewcommand{\headrule}{\vbox to 0pt{\hbox to\headwidth{\dotfill}
\vss}}
to obtain a dotted line instead of the regular solid line. There is
one additional parameter that you can set: \footruleskip. It defines
the distance between the decorative line in the footer and the top of
the footer text line. By default it is set to 30% of the normal line
distance. You may want to adjust it if you use unusally large or small
fonts in the footer. Change it with \renewcommand. Header and footer
height may be altered by changing \headheight and \footskip,
respectively.
Hope this helps,
Werner