I just got the Slim 4gb and sold my old Arcade only to find out that I need an HD for Black Ops. So my friend had an extra 250gb HD out of an old 360 that he gave to me. When he pulled it it was working fine and he had used the data transfer kit to move the data on it to his Slim 250gb. When I plugged it into my Slim it wouldn't recognize it. I tried plugging it into my computer and flashing it with hddhackr but it said it already had the appropriate firmware. So IDK what is up with it. I haven't tried it on the an old Xbox yet but thats my next step. Any ideas?