John,
I recently bought a Freecom model from svp. It seems to do the job fine. I'm not sure if the bundled automatic data backup software is available for a mac, but I dare say this is a common problem with all the drives out there.
There's nothing to stop you manually dragging and dropping the files you wish to copy.
http://svp.co.uk/products-solo.php?pid=1465
Regards,
Duncan