Does anyone have any tips on formating a flash drive/hard drive so that it can be used to tranfer games/profiles from and old xbox 360 to the newly released ones?

I've tried with my flash drives and it doesn't work. And have been unable to find any of the offical ones.

Kinda annoying really... Can't tranfer some certain selet data from my older 360 to my new one.

And I can't use the data tranfer cable as that takes everything and then reformats the older hard drive - which i don't want to, some stuff needs to stay some stuff needs to go.

But if I had a working usb memory device, wouldn't that enable me to tranfer anything i want??