The files are ANSI (Western European), the same as System Default Encoding (I use Spanish Windows XP, but my tests were also in the English version).
I need to work with subtitles (*.srt), many downloaded from Internet or directly generated by me. For testing purposes, I changed their extension to .txt, with the same result.

I tried your suggestion (thanks!) but it only correctly works if I first re-save ALL the files as UTF-8.
Sadly, it isn’t a chance for me, because the subtitler applications don’t recognize the Unicode special chars (with or without BOM signature: they only read ANSI). And saving & re-saving are impossible with the bunch of files of my daily job :-(

If you can to find a way to recognize the ANSI special chars too, PLEASE PLEASE, write me!