SATA uses a different connector to IDE. I don't know if you can get external caddys with SATA connectors yet.
If you where installing a internal drive you would need to have a mobo that supported SATA to be able to use a drive of this type. But i'm not sure how it works when you get to an external drive as you plug in via USB or firewire. I do remember doing an assignment on external storage though and my tutor said that even though the external drive used USB it was still treated as an IDE connection for data transfer rates. This leads me to think that you may need a mobo that supports SATA but i may be wrong.