Your file isnt't a UTF file. Doing the "página" instead of "página" only will bring you problems on future releases.
The standar file works perfectly (portuguese and brazilian guys can't be all wrong". You have to change you server /or admin configuration (Check your locale", ask on portuguese or brazilian foruns, try
http://forum.joomlapt.org ). But if you need UTF suport, why do you went for such a trouble? Why not simple save standard language file as UTF8. Joomla 1.1 has 60 files to translate. Are you ready to change all that?