This is a very good advice. You registration with Amazon might have been used up by your buyer unless its included in the package deal when you sold your kindle. Then you have to register a new your kindle 2.DD said:Yes, definitely deregister it before you send it to your buyer. You don't want it to be associated with your Amazon account or they will be able to buy books from the Kindle on your account.
When you deregister a Kindle, you no longer have access to the Amazon books you bought from that Kindle but your books always stay on Amazon. So, when you register your new Kindle, you can download all the books in your Amazon media library.
When I sold my Kindle 1, I deleted all the books from it, took off any personal information, and then deregistered it. I found out later that if I had left my Amazon books on the Kindle and then deregistered it, the new user could have read those books until they were deleted from the Kindle and then she would not be able to access them from Amazon any longer.
Hope I didn't make this sound too complicated. It's really rather simple when you do it.
Enjoy your new Kindle!
Anyway, You can make your Kindle 2 better. I hope you have accessorized your Kindle 1 which you can use with your new Kindle 2!