Thanks already for the Reply, but isnt it possibly the best idea to wipe everything (accessable without killing the device) a few times with random zeros and ones, and then to create encrypted partitions?

Btw. whats about the third partition e.g "/" is it possible to encrypt it too?

And yea....sad that it seems like nobody yet tried to fully install Maemo onto the MicroSD-Card, that kinda would be the most secure option.
Whats about an encrypted Nitdroid (or even an unencrypted) on the MicroSD-Card.
Would'nt it then be the case that Nitdroid would'nt access nor save files to the internal Memory of the N900, unless you tell to do so?

Thanks in Advance.