fairpoint ok here it goes i am used to xp home as have 2 computers running windows xp home,just picked up a old computer on ebay but has windows xp professional installed wanna unistall and insert windows xp home as have a brand new windows xp home disk basically wanna change computer to windows xp homeUm...any reason you're downgrading to Home? Heh, or should I even ask?
As you begin the install process, there should be an option to partition and format the hard drive. Just format it(unless you have partitions you want to get rid of) and you'll have a fresh start.
I think you should stick with XP pro if you have it. I would do clean install of XP to start on a clean slate, and that involves taking all needed data out and formatting it.