With NT4, I'm pretty sure both HALs were on the CD-ROM (unless you had an exotic system with a custom HAL, which came with its own install media). Keep in mind your use case is approximately nobody, you either had a SMP system or you didn't.

It was really not that rare to want to move a disk from one system to another. Except that there was an obnoxiously high chance that Windows would refuse to boot.