Dear Mekon,
As the FAQ mentioned by Barry says, you have various choices.
If you read my First Impressions Topic, you will see that I used a 1TB Intenso which draws its power from the USB socket. This strikes me as the ideal way to fit-and-forget the recording medium. I formatted to NTFS on the PC and it was recognised at once by the HB. It has been running trouble-free ever since, and I am delighted with the Humax software for it.
Regards. IAINB