I'm guessing I need to partition part of the OS (C:) Drive to equal or less than 500GB.
Make a back-up of that (as well as another repair disc?)
Then... magic (don't feel like explaining, feeling a tad uninspired atm).
ETA: I did get this to boot with the old HDD. Yet.... wondering if it's some other problem, like a network adapter (have no clue here). Guess it's too late for that.
ETA2: And anodda ting... the clicking I heard that I thought was the HDD... It was the DVD/RW drive... must'be been trying to access something when whatever couldn't get info from the HD orwhatever.