I know this, but I have an ASus laptop. It has a start sound like 3 seconds. I was thinking there is a way to add it.
In "program events" find the "event" you want to change .. Add a special .wav file or if you already have a .wav file then hit "browse" and find it .. It's that simple Local disk C: --> Windows --> Media --> find .wav file or add .wav file in this folder