No, there is no way to do that. See this article from Microsoft:
http://support.microsoft.com/kb/303661/EN-US/
How to uninstall Windows XP and revert to a previous operating system
And here is the relevant quotation:
To remove Windows XP, you must have upgraded from Microsoft Windows 98, Windows 98 Second Edition, or Windows Millennium Edition.
Note If you upgraded from Microsoft Windows XP Home Edition, Windows 2000, or Windows NT 4.0, you cannot remove Windows XP.