How to Start Mac Applications Automatically after Login
Mac OS X Snow Leopard lets you configure multiple user accounts. Each account can have its own selection of applications that run automatically when that user logs in. These applications are Login Items, and they appear as a list in the Accounts pane
Before you try to set up your Login Items, these conditions have to be met:
The users setting their Login Items must be logged in: Only the user can modify his or her own Login Items.
Users must have access to System Preferences: If the person is using a standard-level account, it must allow access to System Preferences.
Follow these steps to set your Login Items:
Open System Preferences and click Accounts.
The Accounts pane opens.
Click your account to select it, and then click Login Items.
Click the button with the plus sign
Navigate to the desired application, select it, and then click Add.
Alternatively, you can just drag items from a Finder window and drop them directly into the list. Note that items in the list are launched in order. If something needs to run before something else, you can drag the item entries into any sequence.
To launch the application in hidden mode, which might or might not display it in the Dock, depending on the application itself, click the list entry for the desired item and enable its Hide check box.