Richard,
These items are set to run via the RUN key in the registry. Here are the two
'main' keys:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Of course there are other keys which the are used to run mainly DLL's on
boot like the following:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
NT\CurrentVersion\Winlogon\Notify
The above key is alse checked by anti-spyware applications too
One of the other users pointed you to Autoruns by System Internals (obtained
by Microsoft). This is a fantastic program & gives you so much information
that it may look daunting, but if you look on the Logon & WinLogon tabs
you'll see your antivirus programs. However, the antivirus software also
have 'Services' which are set to automatically run too when the computer
starts
I hope this helps,