Background NEO will normally behave better if you start Outlook before you start NEO, keep Outlook running while NEO is running, and close NEO before closing Outlook.
If Outlook is not started first, some Outlook features and some COM add-ins such as anti-virus tools may not perform properly. For example, in Outlook 2003, Send/Receive will not automatically run on startup when using a POP account, and Norton AntiVirus may not work properly.
For those not using Outlook actively, this may seem to be a waste of memory. However, having Outlook running only minimally increases your memory usage over not having it running because NEO must open and work with a hidden copy of Outlook anyway.
Note that Outlook can be minimized, and in Outlook 2003 it can be moved to the tray when minimized (click the Outlook tray icon then choose Hide when Minimized).
Best way to start NEO You can of course manually start NEO. However you may find it easier to have Outlook start NEO for you:
Enable the option 'Start NEO when Outlook starts' (see the NEO Tools menu | Options | Startup options on General tab)
Always start NEO by starting Outlook (which will then automatically start NEO).