WinXP Home Upgrade Activation?

From: John (John_at_discussions.microsoft.com)
Date: 07/05/04 

Date: Sun, 4 Jul 2004 23:58:01 -0700

HI
i just want to know before i go ahead a upgrade.
my brother bought an HP PC that came with WinXP Home Preinstalled with the product key attached on the side of the case. He recently asked me to upgrade his computer. I'm planning to disassemble his pc and only salavage CDROM, DVD, and Hard Disks. I know this is a major change that will require reactivation. Will there be a problem when i reinstall windows in the new computer?