IIRC they were also using a clever (sneaky) application of copyright law to enforce this. They used a few special sectors on the disk to store an image to whic

IIRC they were also using a clever (sneaky) application of copyright law to enforce this. They used a few special sectors on the disk to store an image to which they hold the copyright. The Xbox checks to make sure the image is there in the right spot before it will use the drive. So you can't pass off another drive as valid without violating their copyright.