Welcome, teealmee! You'll find this to be a very friendly place full of great people and information! Hope you enjoy your time here!
Now to answer your question, touch the Menu soft key (four bars on the bottom of the Droid) go to Settings > Sound & display and scroll down to SD card notifications. If this is unchecked, the 'DROID' sound won't play when you boot up. If it is checked, the sound will play. Hope that helps!