Actually, if you are never going to want kepub versions of the books you bought prior to buying a Kobo device, you could just start a new account and use that one with the device. You can continue to get epubs of your older books using the old account.
My husband has an account that he has never used to purchase a book. He uses one of my readers (hehehe) and he reads the ePubs of the books I have bought. He updates his firmware using his own account. No books involved.
Last edited by taming; 04-22-2013 at 06:32 PM.