In your step where you copied and deleted drive filling DVD images, then defraged..then Eraser..
Could I comment.. running eraser, then defragmenting the drive first in a remote situation (aka from BartPE or with the HDD in another PC), then a couple of times in normal mode. Then run eraser again.
With encryption of the data before doing any of the above.. I question this.. as the process of encrypting will invarably rewrite the data to differen sectors, potentially leaving the original data (while deleted) in the original sectors un-encrypted.. unless the encrypting app encrypts sector to sector..not file to file as many do.