Steve, it sounds bad alright. There are a lot of places where the problem could lie. Of course, the drive might be bad in some way. One intriguing observation is that you don't hear the drive running. That could mean it's not getting power, so it could be a power supply problem. Try switching in a different power cable, if there is another inside the box.
Even if the motherboard is bad, I would expect the drive to spin up. To test this theory, unplug the *data* cable from the drive and leave the power cable plugged in. When the system gets power, the drive should get power and spin up.
The next procedure to try would be moving it to another system. First connect the power cable and see if it spins up. Then connect the signal cable and see if it's recognized. Keep in mind that it's unlikely to damage a system it is put in, but it's still possible. Be sure to account for this worst case scenario when diagnosing the drive.