Yes, as long as you have a "retail" and not an "OEM"
Windows XP license. However, you should know that
your laptop manufacturer will no longer offer any
technical support if you should have a hardware issue.
Additionally, since laptop computers require specialized
hardware drives, you need to first check the laptop manufacturer's
support web site and see if they have Windows XP drivers
available, such as video adapter, audio, NIC, modem, etc.
If these functionally important Windows XP drivers are not available for download,
then you need to to stay with Windows Vista.
Clean Install Windows XP
http://www.michaelstevenstech.com/cleanxpinstall.html