How To Get Your Free Migration Cable
Elle has a good article on the Xbox 360 Elite SKU:
http://www.xbox.com/en-US/community/personality/elle/20070427-xbox360elite.htm
In that there is information regarding the migration cable:
http://www.xbox.com/en-US/support/systemuse/xbox360/console/datamigration.htm
And in that article there is a PDF and instructions for new elite owners (and previous 360 owners) to get their free migration cable:
How to Get Your Free Transfer Cable
There is alot of good information in the two articles that I link to, so I recommend you read them.
(images courtesy of Xbox.com)