favorite sound or song...do like below..
First of all u need an audio file which we have to use on start up with .WAV format...If u no converter to convert audio..then click below link to download the simple converter called ... AUDACITY
Go to:
http://audacity.sourceforge.net/download/windows
After conversion of audio file.then navigate like this..
START>CONTROL PANEL>SOUND,SPEECH AND AUDIO DEVICES>SOUNDS AND AUDIO DEVICES
A new notification window could be opened...then click on SOUNDS tab..On bottom of that window on PROGRAM EVENTS scroll that events and u will find START WINDOWS..
On the lower bottom u find small type of player and some sample audio file eventually u will play that sample by clicking play botton..On right side u will find BROWSE tab..By clicking that tab u cab able to put an external audio to that notification window then add ur favorite audio.wav file to that notification window ...then APPLY>OK...
Thats it the system start up sound will changed into u favorite Audio...