Removing Win XP Pro

I have installed WinXP Pro over WinXP Home. I want to get rid of the WinXP Pro. I am finding out that I cannot reinstall WinXP Home over the Pro. Do I have to do an fdisk in order to install my WinXP Home. I have a dell with a restore CD. Can I use that to install my WinXP Home after an fdisk?
(I do not have a restore point prior to the WinXP Pro install)
Thanks for the help….