In order to read the vietnamese document, you will need a vietnamese ttf font produced by vps (Vietnamese professional society - hoi chuyen gia viet Nam). please take note or print out this procedure:
Beside three provided fonts in vpsfonts.exe, you can get a lot more VPS, viscii fonts at ftp://ftp.media.mit.edu/pub/Vietnet the installation method is a bit difference, because those font files at vietnet directory are zip files. you need to extract the font files into a directory and continue from step 4 above. at the same place, you can get vpswin3d.zip (vps keyboard) or winvnk14.zip (viscii keyboard) which allows you to type vietnamese characters in your text editors.
Have fun!