Hitachi? I've not had good experience with them... I've had about 3 of their drives die, while I've never had a WD or Seagate die. I know it's not a question of if, but of when, but still. I don't trust Hitachi, but as always YMMV.
My vote is for Western Digital or Seagate, in that order. Find something that's 7200 rpm as well, they're much faster than 5400 rpm drives.