1) Got a USB drive? I recommend backing up some of your stuff on it before you start any of this.
2) Found this here about transfer kits:
http://forum.teamxbox.com/showthread.php?t=633507
The first version that ends in a -01 and -02 will not work with the 250gb drive. The 2nd and 3rd versions will work with the 250gb drive and work on drives that have been transferred in the past.
Here are the known working disc numbers.
This is the one I used.
Media Set: X13-45472-03
Part No: X13-45328-04
and
Media Set: X13-53192-03
Part No. X13-45328-04
Any numbers higher then those will work since it would be a newer version of the software.