http://www.xbox.com/en-GB/support/systemuse/xbox360/console/datamigration.htm

Has anyone used it? Can you get drivers to allow you to connect it to a PC?

I have not used it yet, but the cable is on its way to me. It transfers all the data off an old 360 drive to the new one. It's pretty much for folks with Premiums who either buy an Elite or the 120gb hard drive and need to put their data on the bigger drive. While I was trying to do this recently, I found out the new drive I got has a few downloads that I want to see if I can use (Oblivion 'Shivering Isles' DLC) and a few others. If I can use the data and it's not locked to someone's profile and/or 360, I will keep it. If not, off it goes and I'll use the cable.

EDIT: I played Oblivion and indeed I can use the Shivering Isles DLC - I accessed the Isles content in-game, so I won't use the transfer cable after all.

I used it a few weeks ago when I upgraded from a 20gig to a 120gig and it wasn't bad.

It took a while for it to recognize that the USB transfer cable was plugged into my 360 (have no idea why that part was so hard) but once it finally realized I did have my cable plugged in it was easy.

You just make sure all USB devices are unplugged (including wireless adapter), inset the disc that comes with it, plug in your new hard drive to the USB cable, and then follow on screen instructions. It's pretty easy.

I think it took about an hour and a half to copy everything but I actually just started the process and then left for a few hours and came back and it was all finished.