Writing text in farsi in MSWord 2003

hello there, I have Windows XP on my computer as the operating system and MSWords 2003. I have been trying to use Farsi with my MSWord. When I go to control panel/Regional Languages, to choose Farsi(Persian) it doesn't exist. I click on Right to Left button in "Detail" I get a message asking for some software which should be on "Windows XP Home edition, Service Pack 2", I insert this CD but it can't find the files that it is asking for. Don't know what to do. Can you please help, it is so important to have Farsi software for my job........would appreciate your response.........best........shirin