Do you have video card installed as well?
As for the hard drive you could get a desktop hard drive, Take it out of the enclosure and install it in the PC then install Windows on that.
---------- Post added at 01:48 PM ---------- Previous post was at 01:47 PM ----------
Seagate Barracuda 1TB ST1000DM003 [ST1000DM003] - $69.00 : PC Case Gear
I tried using a portable harddrive, which worked at frist, like all my steam games ran properly, then out of the blue, steam wouldn't work of it, neither did other games.