one small and the other even smaller, about an half cm height.

I think the one that was about half-cm tall wasn't a 2.5" notebook IDE drive. It was probably a PCMCIA-card drive, not a 2.5" IDE drive.

Why would you want to use a PCMCIA-card drive in your empeg, when the 2.5" drives are cheaper per gigabyte, and you can get them in larger storage capacities.