I Want to Change CODEPAGE in windows XP

[DrDelphi2003]

I wrote a delphi program in farsi. but it dosen't work properly (bidimod=RighttoLeft Don't work) unless I changed Code Page (in control panel --> Reginal and language setting) to FARSI.
I want My application test this code page if it wasn't true. my program change it to FARSI.
May you Help me!
I can suppose that Farsi has installed but not set for windows.
Thank you.