oA9999 0 Junior Poster in Training

Help guys...why is it that I cannot change my Vista to XP Pro SP3?
When i tried to boot my PC to the bootable disc of XP SP3 and when the setup is finished, BSoD occurs..

Is anybody here can identify what's with that error?
I can understand BSoD..
It has many numbers and words..hahaha
Please help me..

Thanks..