Sysinternals has a great freeware tool, Autoruns, that gives a graphical view of every application and plug-in that initiates when you start your machine, as the figure shows. The tool also lets you hide standard Microsoft components, so that you can view third-party additions more easily. You can download the tool here. The download includes both the GUI version and a command-line version of the tool.
You can stop an application from executing at the next start-up by clearing the check box next to the application. If you want to remove an application permanently from the startup items, select the item, then select Delete from the Entry menu. The download includes full Help documentation.