Upgrade from XP Home to XP Pro

[Guest]

I have inherited a computer that will be replacing my existing computer. The
inherited computer has XP Home. The computer to be replaced has XP Pro. How
can I replace the XP Home with XP Pro? If I insert the XP Pro disk into the
replacement machine will it automatically upgrade or must I reformat the hard
drive in the replacement computer?
Thanks

 

[Jerry]

Boot from the XP Pro and CD and opt to do an upgrade.