Sounds like that would be the problem. The replacement hardrive did NOT come from an Illico box, it's just a standard off-the-shelf PC hardrive I formatted on a Windows-based computer and then stuck in the 8300HD (without a Videotron cable hook up).
I called Videotron a few weeks ago and they said the MAC ID on this 8300HD was free to register if I wanted to, I just had to call them back (prior to that it was registered to another owner and locked).
Problem is I don't want to pay to have it registered and then find out it doesn't work. :P
I'll try hooking it up to an active cable line and see if causes the firmware to kick in and partition the drive properly.