Use tip 5609 ยป How do I assign scripts in Windows to assign a startup script to each PC in the domain.

To make every user that logs onto the domain a local administrator of the PC they logged on from, the start script should contain:

@echo off
setlocal
set OK=N
<font size="1">for /f "Tokens=*" %%a in ('%SystemRoot%\system32\net.exe LOCALGROUP "Administrators" ^|%SystemRoot%\system32\find.exe /i "NT Authority\Interactive"') do (</font>
 set OK=Y
)
If "%OK%" EQU "N" %SystemRoot%\system32\net.exe LOCALGROUP "Administrators" "NT Authority\Interactive" /ADD
endlocal