First thing I'd do is turn off the ato boot setting if it is turned on.
Make sure you spend some time going through all of the menus on the dashboard, get yourself straight to the demos section of the game marketplace and start downloading. One thing that some people don't realise is that you can play video files directly from a USB stick in the front (or rear) of your console with a quick automatic update.
You can also install games to the hard drive to save it spinning up the DVD, simply click Y instead of pressing A to play a game when on the My Xbox menu and then choose install to hard drive.