Welcome to MobileRead iansealy!
Unfortunately, Kindle books cannot be read on a Kobo without removing DRM and converting to ePub, which would probably be a pain for your Dad (even though there is an Australian Kindle books store).
Are you unable to purchase a Kobo gift certificate for him to use? You can also check other ebook retailers that sell the ePub format (Sony, Fictionwise, BooksonBoard). I'm not sure that Barnes & Noble ePub will work as they have their own type of DRM.
I'm sure some more knowledgeable folks will pop in with more specific advice for you.
