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!