That was the best move there. Hopefully you didn't have too much trouble transferring since some items like supplies on older prebuilt systems use different ways of mounting like different bolt patterns for supplies like seen with the older Dell models.
I ran into the same problem when going to upgrade an old Socet A case here with everything seeing higher temp on the 939 board until moving everything out into a new case with a large fan right on the front.
One thing to know about hard drives however is that they will take more heat then a more sensitive to temp item like a cpu. Just look over any old case whether Intel, AMD, or some other to see hardly any vents let alone fans in the front or side except as seen on older gaming systems.