I've done some research on How to install Windows OneCare silently and here what I got: - Start the Windows OneCare Setup (mine: SetupOneCare.exe). - Let it start and finish download. - Go to c:\program files\Windows One Care …\Staging and copy this folder elsewhere. - Cancel the setup of OneCare (SetupOneCare.exe) - In the copied "Staging" folder, there's the setup of Windows OneCare, called WinSS.msi And to start it silently: @echo off Echo Installing OneCare 2.5... msiexec /i WinSS.msi /qn exit Have fun guys! Matt