I was able to install Norton Internet Security 2006 silently using this command in WPI:
%CDROM%\Software\Apps\NIS\SymSetup.EXE /O REBOOT=ReallySuppress /qb
When I use the same command to install Internet Security 2007, I get a window that pops up on reboot that says:
cfgwiz
Failed to launch _tInternalWinMain
OK
Has anyone silently installed NIS 2007 successfully?