Special characters for Foreign Language Translations

I'm not sure if this is a game engine question,
a publishing question, or a Windows question, but here goes...

We have a client who would like us to do a Portuguese Version of a Torque based game we did for them a while back.

The Game, Deliverance uses straightforward .txt files as "subtitles" for in-game conversations.

The client has provided us with translated .txt files that contain numerous special characters (accent marks, etc) that show up fine in Notepad/Wordpad but DON"T show up in the game... replaced by the little square [] indicating the missing character.

I've tried setting my computer to Portuguese as the main language, I've verified that the font we're using has those special characters, to no avail.

Has anyone had to deal with this?
Is there a windows setting I'm overlooking?
Is there anything about TORQUE that would prevent these characters from showing up?

Thanks!