I've installed Ubuntu on all of my family and girlfriend laptops and there's not ONE of them who hasn't complained about the annoying (and according to my mom, creepy) startup sound. Searching for sound themes on the net is really a pain, because it's scattered all around websites and you never know if what you're downloading is what you're looking for or not. And the default sound theme definitely needs some attention (it's the same since Edgy, isn't it?).