SX-antecs are really tough to beat. The front grille is functional and basically wide open, and the stock stamped metal case grilles are excellent, meaning that really quiet fans will give good airflow. The hdd can mount right behind the front air intake, you can ditch the hdd cooler. Thick sheetmetal, very good fit&finish, excellent features.
If you're happy with your psu, do a search on pricewatch for sx600, sx800, sx1000. these are the various models w/o psu. 80mm panaflo L1a fans or Silencer fans will do a good job in one of these low restriction cases.... Cool and quiet, just what you want.