Sorry for the dead post resurrection, but I have realized this has become the #1 search result for people trying to find how to type Arabic Digits (Hindi Digits) in Windows 7. After looking into it for a few months, the problem stems from Microsoft's Arabic package not including the characters. So after a few hours the other day, I have created my own KLC that includes all of the Hindi Digits with the arabic characters in the letter area. It can be found on my website here: RyanGlynn.com » Arabic Keyboard Layout Finished Programming!
-- The zip file contains a microsoft self installer so just run it and Arabic 103 will be created in your languages for keyboards.
Hopefully people with the same need as me will have their issue solved through my KLC.
Please direct all issues/questions to the post on my website.