I encounted problem exactly as many people in maillist
archieves describe: give back invalid argument error
repot. I do exactly what the readme tell me to. I think it
is better to write explicily : edit the gp_win32 file and
edit the line as:
gnuplot_command = r"d:\Python23\gp400win32
\gnuplot\bin\pgnuplot.exe"
this may reduce a lot pain from windows user.