Could be something like this: Autorun.inf: [AutoRun] open=sp2.cmd sp2.cmd: WindowsXP-KB835935-SP2-ENU.exe /passive /norestart Use /? with WindowsXP-KB835935-SP2-ENU.exe to find further switches if you want to change it. All of autorun.inf, sp2.cmd and the service pack should be in the same location for the above to work.