From what I can tell, the 80G WD drive was married to the bad EEPROM the first time you tried to log onto XBL. When you switched the EEPROM afterward, you caused the marriage to change, and got the system banned from XBL.
As for the swapping back to the original drive, I have a question for you. Were you ever on XBL before you upgraded to the 80G WD drive. If you were, you broke the marriage again when you got the fresh EEPROM and matched it to the original drive, instead of using the original EEPROM that was married to the drive.
The solution:
Unfortunately, both of your HD's are now flagged as unmarried, so you have to get another new drive.
Money goes out the window when things go wrong. You also need a new fresh EEPROM to marry to the new drive, because all of you current EEPROM files are flagged.
GL to you in the future, and I truely hope you get on XBL again soon.
Megahurt