OS not found

WHen you say neither of these 2 machines can find the HDD do you mean "OS Not Found"? Or do you mean that BIOS cannot detect the drive? There's a big difference between the 2....

SOmetimes, when moving a functioning drive from one machine to another, the second machines bios will not detect the drive using the same head/cylinder/sector values as was used when the drive was formated/installed in the previous machine.
This reasults in the new machine's bios detecting without error, but presenting a drive with an unreadable partition table.

I would put the drive BACK into the older, functuioning machine where the drive works properly, enter BIOS, and record the Head/Cylinder/Sector paramaters that this machine is using for this hard drive.

Return the drive to one of the non-functioning machines, allow bios to auto detect again, and view the head/cylinder/sector paramaters that the new machine is attempting to use with this drive.

Are they different? often you can choose from several choices, or manually configure these paramaters. Whatever the case, I would ensure that the new machine is using the same H/C/S paramaters as the old machines...

Good luck...

Does the hard drive spin up? Does the CD drive light up? Could be power supply/cable issues.

Definitely verify that the BIOS can find the devices on bootup. Most relatively modern drives will not need you to manually enter in the hard drive specs; you can usually set the IDE channels to Auto or somesuch.

Also, check the master/slave/CS jumpers on the drives themselves.

Bonne chance.

Sig9