You can convert any ebooks into mobi format by using a free program called Calibre. It is also very useful for keeping a catalogue of your books as the only downside I find to the to the kindle is that you just have a list of titles and I can never remember what the books are about, comes of downloading so many free books! I just keep a note in Calibre and I can check to see what I want to read next.

You can use it to send things to your kindle too, and it will also convert pdfs which can be tricky. (You have to email them to amazon, not hard just not so straightforward.)

Enjoy your present

Alison