Loading XML values with special character (à, é, ù, ....)

When I use the character substitution presented at

http://www.commentcamarche.net/contents/489-caracteres-speciaux-html

it works on Mac with

<?xml version="1.0" encoding="ISO-8859-1"?>

or

<?xml version="1.0" encoding="UTF-8"?>

in the first line.

The same thing is not working for windows....