I haven't even seen a 9x box since, well, the 90's. The moment I got NT4, that pretty much spelled the end ff 9x for me. Never really looked back... (all my machines have XP and 2K on them, and I still have one NT4 machine).

That said, I'm certain there may be simular call that could be made on a 9x, and if not, then a protection probably won't be able to use the NUL trick on a 9x box. It is not uncommon for protections to fall back to other methods when things don't work.