WD My Book Duo is pre-formated with with NTFS, I am using it right out of the box. (Text from WD Product page: My Book Duo ships preconfigured in RAID 0 for maximum performance. Pre-formatted NTFS, My Book Duo is ready to use right out of the box for Windows OS users.)
http://www.wdc.com/en/products/products.aspx?id=1260
But this is not getting recogniged when i plugged into USB port of WD Live Hub.