wiping drive?

martin, you stated wiping drive, is that the way to take off vista to install xp pro? I have decideded not to keep vista but I am hesitant to try installing xp pro, because of research I have done regarding vista home premium, they state the business or ultimate are the only os that you can downgrade from , have I misunderstood what they are talking about and should I attempt to do this myself or find a computer tech to do it?