I've only heard rumors about the M$ factory return xbox not being moddable.
till recently I thought it was a myth, I've been able to mod every xbox version.
I got one of these xboxes from a local shop that mods them asking me to look into it and figure out what my options are.
yeah, you guessed it........
it's now modded 
here's how
this project is not for the first time modders.pop in the gamsave exploit and load up the M$ dash, copy the game save to the harddrive.
restart the xbox and pop in the game, choose the run linux save ( if you have 007 - you have to play for a few seconds and save first )
once this screen comes up do the backup option
nest step is install the softmod.
((( this is where the M$ return wont let you continue )))so.... FTP to your xbox and grab that
eeprom.binput it on a floppy disc and use this tutorial >
http://www.smdepot.net/forum/index.php?topic=85.new#newthat tut will let you completely rebuild your harddrive and make it moddable.
this project is not for the first time modders.if you end up having one of these xboxes I suggest shipping it off to smdepot.
if you have any questions on this or want real time live help goto our chat room on irc
http://www.smdepot.net/irc/chat.phpBOOST = 19,923,655,515,520
M$ Xbox = 0
BOOST