If you're looking to dual-boot between Mac OS X and Windows XP with Service Pack 3 (SP3), you'll be interested in this Boot Camp update:

Boot Camp Update 2.1 for Windows XP

About Boot Camp 2.1 for Windows

This update addresses issues and improves compatibility with Microsoft Windows XP and Microsoft Windows Vista running on a Mac computer using Boot Camp. It is highly recommended for all Boot Camp users.

Important: Installation of Boot Camp 2.1 is required before installing Windows XP Service Pack 3 (SP3)

For more information, please visit this website: http://www.apple.com/support/bootcamp/