I recently wrote a language script.
Maybe you'll find this usefull:
if(ereg("de", $HTTP_ACCEPT_LANGUAGE) == true || ereg("de-([a-z](2))", $HTTP_ACCEPT_LANGUAGE) == true){
include(language/de.php"); //German file
}
elseif(ereg("es", $HTTP_ACCEPT_LANGUAGE) == true || ereg("es-([a-z](2))", $HTTP_ACCEPT_LANGUAGE) == true){
include(language/es.php"); //Spanish file
}
else {
include(language/en.php"); //English file
}
Check your Browser Settings for other language abbreviations (ie. fr, se, no ...)