That's a stupid lie. EEProm contains:
XBOX SERIAL NUMBER
XBOX MAC ADDRESS
XBOX ONLINE KEY
XBOX VIDEO MODE
XBOX XBE REGION
XBOX HDD KEY (my Xbox is dead ATM and I can not verify it

)
XBOX CONFOUNDER (dunno what it is, so I'm puttin' it here

)
And how do you think; that after changing the hdd EEProm changes just like that? LOL, you're funny, it looks that you've never been playing with CM. Try editing EEProm on the fly and try to change hdd s/n

.
And the things that have to be changed in an EEProm to make it 'new':
XBOX SERIAL NUMBER
XBOX MAC ADDRESS
XBOX ONLINE KEY
--------------
Taken from xbox-linux.org:
The serial number looks like this:
418932 33205
LNNNNNN YWWFF
FF is the code of the factory (02: Mexico, 03: Hungary, 05: China, 06: Taiwan), L the number of the production line within the factory, Y the last digit of the production year, WW the number of the week of the production year, and NNNNNN the number of the Xbox within this week.
-----------------
Change only one N of the NNs value. Nothing more! The MAC adress: change of the digits- whichever you like and for the Online Key... I don't know

. Try to change one of the digits that you like/ don't like

. Shall work after this. BUT: remember that you can ban an innocent person! Remember that it won't give you 100% guarantee to unban you and make a fuckin' backup of your EEProm (even banned as long as it works good with everything else), befeore playing with CMF.
It's all just to give you some sight on the case. I think that there might be some holes/ mistakes in this info

. I don't and I won't try this method, cause I don't have any modded Xboxes and don't wanna get banned/ don't want my GT to be flagged.