Settings...Sound....SD Card Notifications. Just make sure the box is UNchecked.
Ya. I don't have the "Drooooid" startup sound, but I can't remember where I turned it off. It's in the settings somewhere. And, I'm not rooted.
Same here, I don't have the robotic "DROID" sound any more, but I don't remember turning it off or learning how to! I guess with the hundreds of things I've had to learn about this device I haven't been able to commit all of them to memory.