Regarding Windows 2000, your computer would need to support the ACPI Bios standards to enable an automated Power-Off after shutdown. How old is the computer? Pentium II's and above, for the most part, should support ACPI.
Check the computer mfg or Bios vendor for an update if applicable.
As for NT4, it "barely" supports APM (Advanced Power Mgmt)
and consequently requires outside support to get many of these features to work. Namely an OEM HAL.DLL that supports the power off with the addition of a registry key set to enable power off after shutdown.
If you enable it in the registry and the Hal.dll support is not there, then the computer will restart when you choose to power off.
I think the registry key is the same for W2K as it is for NT4:
HKLM/Software/Microsoft/WindowsNT/CurrentVersion/Winlogon
Key is "PowerDownAfterShutdown".
Doug
dxd_2000@yahoo.com