To prevent the programs in the Startup Folder from running when you logon, hold down the shift key immediately after entering your password in the NT logon dialog and hold it down until the desk top appears.

There are multiple methods for applications to be started. The startup menu is one of several. To better monitor what is started up (with significant control), check out:

Startup Control Panel

Startup Cop

Startup Manager

Covers installation and support of NT Workstation. If you are just getting into NT workstation, its a good book. If you are experienced NT techie, forget it.