Is there a superglobal reference to the user's country or is using the IP against a database of IP to Country lookups the best way to go?
i wish there were such thing as $_SERVER['HTTP_COUNTRY']... maybe in php99 ? ;)
for the time being, http://php.net/manual/en/book.geoip.php is your best bet
however, if you're only interested in user's language, there is $_SERVER["HTTP_ACCEPT_LANGUAGE"]