I don't have 2k to test on... Ruud said he would be unavailable for comment for a couple of weeks... so hopefully someone else can confirm this. In the mean time you could do something like this in a bat file:

 Code:
@echo off

ver | find "2000" > nul
if %ERRORLEVEL% == 0 goto oldkixexe

ver | find "NT" > nul
if %ERRORLEVEL% == 0 goto oldkixexe

ver | find "98" > nul
if %ERRORLEVEL% == 0 goto oldkixexe

ver | find "95" > nul
if %ERRORLEVEL% == 0 goto oldkixexe

::For all other OSs
:start
kix32.exe scriptname
goto exit

:oldkixexe
kix32_453.exe scriptname


:exit