There is no way of downgrading Windows, so a clean install (wipe everything and start from scratch) is necessary. In addition, the Home editions do not qualify for free downgrade rights, so you would have to purchase your own license for Windows XP. Thus, unless the manufacturer offers a free downgrade you are looking at purchasing a new license at full price.
I bought a laptop w/vista home pre-installed. Is there a way to downgrade to XP home? I see upgrade versions from 98 & ME to XP
but nothing downward.