I think I've discovered why my HD speed is much slower. The notebook IDE cable that comes with the VoomPC-2 case is not 80conductor type and therefore cannot support higher transfer speeds.
I have a spare IDE notebook adapter with 80 pin conductor cable but the adapter hits my Kingston RAM. Relocating the hard drive to the CDROM drive bay didn't help either.
Replacing the DIMM with a shorter piece might fix the problem, but I think going to SATA will be the best choice for this motherboard/case combo.