After too many hesitation I decided to reinstall NITDroid by testing the brand new Auto installer! Everything went fine except that in the multiboot, I have four entries:
1 - The stock Kernel
2 - NitDroid rc kernel (I tried to boot with this option and it booted to maemo with the kernel - weird...)
3 - Power kernel
4 - NitDroid

No major problem for me, but how can we do if we want to delete the unused entries (such as Stock kernel and NITDroid kernel) ???

Own Appreciation: @Ammyt: You have done a good work with the Auto installer, but don't forget to mention in the wiki that users could download the NitDroid image separately and copy it to MyDocs, then run the installer!
Anyway, Thanks a lot and (@E-Yes if you read me: we are dying to wait a full stable release of NitDroid)