The Xbox 360's original graphical user interface was the Xbox 360 Dashboard; a tabbed interface that featured five "Blades" (formerly four blades), and was designed by AKQA and Audiobrain. It could be launched automatically when the console booted without a disc in it, or when the disc tray was ejected, but the user had the option to select what the console does if a game is in the tray on start up, or if inserted when already on. A simplified version of it was also accessible at any time via the Xbox Guide button on the gamepad. This simplified version showed the user's gamercard, Xbox Live messages and friends list. It also allowed for personal and music settings, in addition to voice or video chats, or returning to the Xbox Dashboard from the game.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): The simple dashboard could be accessed by pressing what controller button?
the Xbox Guide button on the gamepad