Welcome to MR, Chema
Congratulations on your iLiber. If I understand correctly, it reads ePub and prc?
Our MR library has beautifully formatted ebooks in the
ePub and
mobi / prc format.
If you would like information in Spanish, there is
a forum for the iLibre on
lectoreselectronicos.com (A Spanish site by MR member surquizu).
I have the Sony 505 and love it. I don't have any experience with the Sony PRS900 nor the Kindle DX. I imagine you will get lots of information in those forums plus you can check out our
E-book Reader Matrix in the MR Wiki.
Have fun exploring the forums and ask if you have questions.