Windows XP can create a R=E9sum=E9.html file but ruby cannot.  Why?

The following code  created the wrong filename
    File.open("R=E9sum=E9.html","w") { |file| file.write('xxx'); }

Also, this code does not work
    str =3D "R=E9sum=E9.html"
    filename =3D Iconv.conv('UTF-16','UTF-8',str)
    File.open(filename,"w") { |file| file.write('xxx'); }

If I manually rename the file to R=E9sum=E9.html, it does work.

Setting the $KCODE=3D"u" or $KCODE=3D"UTF8" makes no difference.

Whats wrong with ruby v1.8.7 (or is it me)?