I tried several HDs actually, it wouldn't recognize any of them (from previous laptops). I tried a WD Scorpio, Seagate momentus, and a fujitsu. The one in my mac originally is a hitachi. It would not recognize any of them except the original hitachi one.
The only thing i noticed that is kind of different is that all the others have like four pins on the side of the SATA connector, and the hitachi one doesn't seem to have it.
Nope, I only have one mac. I would like to try it in another one and see too.