@ECHO OFF
IF NOT "%OS%"=="Windows_NT" GOTO Syntax
IF      "%~1"=="" GOTO Syntax
IF NOT  "%~2"=="" GOTO Syntax

SETLOCAL
ECHO.%~1 | FIND "\" >NUL
IF ERRORLEVEL 1 (
	SET Domain=%UserDomain%
	SET Name=%~1
) ELSE (
	FOR /F "tokens=1,2 delims=\ " %%A IN ("%~1") DO (
		SET Domain=%%A
		SET Name=%%B
	)
)
FOR /F "tokens=*" %%A IN ('WMIC Path Win32_UserAccount Where "(Domain='%Domain%' And Name='%Name%')" Get SID /Format:list ^| FIND "="') DO SET %%A
ECHO.%SID%
ENDLOCAL
GOTO:EOF


:Syntax
ECHO.
ECHO User2SID.bat,  Version 1.00 for Windows XP Professional and later
ECHO Return the SID of the specified user ID
ECHO.
ECHO Usage:  USER2SID  [domain\]userid
ECHO.
ECHO Note:   if no domain is specified, %%UserDomain%% will be assumed
ECHO.
ECHO Written by Rob van der Woude
ECHO http://www.robvanderwoude.com