Unable to chnage vista to xp (hp dv6626us)

Hello,

haiiiii

i bought a new hp pavillion dv 6626us laptop
intialy it was in windows vista .now want to change os to windows xp
when i am trying to formate by using xp cd a problem occered there!!!!
i skip nearly 5 files that anable to load during process......
another problem ocered there is hard driver not found
now how can i change the os vista to xp

plzzzzzzzzzzzzz help me to change the os

now the is continiously restarting when i on the power button.............../

plzzz help me