Greetings,
OS: XP Pro, SP3
To start Outlook minimized with an icon in your system tray at boot, you create a shortcut to Outlook.exe in your "Startup" folder and then right-click the shortcut and choose "Minimized" for the "Run" option.
With this method the Antispam toolbar does not appear when you maximize the Outlook window from the tray icon. If you choose "File -> Exit" and restart Outlook normally, the Antispam toolbar appears.