well, since you listed a friend with a modified xbox in your tut, and you said you based that tut on what you did, this is how my neighbor did his softmod a while back (with my xbox being the chipped one). this method has its risk's involved, but worked for him.
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here is how it is done
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set the 2 xbox's side by side opened up
put the bigger harddrive in the chipped xbox
get the bigger harddrive all ready to go into the UDE xbox (install exploit get files on the hdd etc.)
with the retail hdd in the UDE xbox, start it up, and load up config magic, where it says press any button to continue, don't do anything yet.
start up the xbox with the chip and bigger harddrive.
pull the ide cables out of both harddrives, and connect the UDE Xbox's IDE to the bigger harddrive (with the powercable from the chipped xbox still in it.
Hit a or start or whatever on config magic
lock the drive
power down both xbox's, put them back together.
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here is the reasoning behind it
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a harddrive will only boot on an xbox without a chip if it is locked. to lock a hard drive, it gets its key from the eeprom on the mobo. each key is unique to the eeprom. this means you must lock your drive in your UDE xbox, however you can't boot it in there because its unlocked. you prepare the drive so its all set, then load up your retail hdd in the UDE box, this will load up and let you get to config magic (the program you lock drives with), at this point, you need the bigger harddrive in, however you must keep all the harddrives powered up, so you only swap the IDE cable over. now your bigger harddrive will be locked by the UDE xbox.
keep in mind this method has its risks as you are performing a hotswap with the harddrives, i have performed this 1 time with a friend, and nothing went wrong, however there is that potential. (as you said in your tut, BLAH BLAH BLAH screw up the xbox BLAH BLAH BLAH
![tongue.gif](http://forums.xboxscene.org/html/emoticons/tongue.gif)
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it is possible to lock the drive in the pc but i don't know much about this method, you will get the key to lock it with from config magic on your xbox.