Well, they do allow you to mute the startup sound, but you are not allowed to change it. The reason why is that Microsoft spent a lot of money paying Robert Fripp (of King Crimson fame) to come up with the sound, and they want to be sure that this signature sound is played every time Windows starts. You will notice that there are sound event entries for Windows Exit, Logon, and Logoff. You can play them and change them as you see fit, and even save this as a custom Sound Scheme. When you open the Sounds control panel and select the Sounds tab, you are presented with the current Sound Scheme and a list of sounds attached to program activities and various Windows events. How to Change the Startup Sound in Vista
