ParsNegar: 
It is a simple program that allows you to write in Farsi,
save it as HTML file, attach it to your e-mail and send it.
The receiver opens the attachment and reads it.
If the ParsNegar font is not already installed on the recipient's computer,
it will be prompted to download it for free
and install it. Parsnegar costs $35.00.
 
If you are interested to write Farsi with Windows:
Down load Farsi Program from here:
http://www.mostafaheravi.org/Farsi.html
Install Farsi program for Windows XP
Save, Unzip and run it to install.

Next time when you turn it on, any time that you like to type Farsi,
just Hold Alt and click Shift on left side of keyboard
and if you repeat it again, back to English.
Also you can do it the same on right of keyboard,
to change write from right to left or left to write.
If you like to have nice Font, you can install Nazanin Farsi font.
You can download it from here 
http://www.tarjomeh.com/fonts/
and install it, or search Google for Nazanin Farsi font.
There are so many other beautiful fonts that you can choose. 

If you like to change from to graphics,
you can use it Power Point or Paint Shop Pro.,
or many different other program and use is cut and past.
The advantage of this method is that everybody can read it.
The disadvantage is that is takes lots of space. 
Good luck.