Have you considered the possibility that it could be Motherboard Resources to blame? It's easy to see these resources in any other Windows OS other than NT4, from the Device Manager. It is a little different trying to tweak these parameters in NT4.
Also remember that NT4 is not a Plug 'n' Pray operating system, so it won't sort out the resource allocation for you (also, remember there could be a switch for this in the BIOS). It will take the parameters that are saved to the OS and if they don't work, the boot-up will fail. Unfortunately, these parameters are configured when the OS is installed, so it could be possible that the only way to get that disk working as a primary master, is to re-install NT4.
Just a thought.