Urgent – quick q about installing new windows os

im about to install from boot cd windows xp and i have the disk burned. However i have 3 previous installations which every time i’ve re-installed it i havent been able to get rid of, other than a ‘windows.old’ folder in HDD. I want to factory restore?
Answer #1
Just format the C partition during windows setup.
Answer #2
As Roberto said, just format the whole C partition. Clean install