As long as it's the same version (Home for Home, Pro for Pro, no 64-bit if you have 32-bit)...and it's a Microsoft XP install CD...you should be able to do so. Some say that's not so...but I've never dealt with the circumstances they cite.
I emphasize Microsoft install CD...because most of the documentation for such was not written for "recovery disks", "restore disks" and such.
The key/license is....well, it's the "key" item
. The CD is just a storage device for facilitating the installation of the needed files.
XP Clean Install, Stevens - http://www.michaelstevenstech.com/cleanxpinstall.html
Differences between a Quick format and a regular format during a clean installation of Windows XP - http://support.microsoft.com/kb/302686
Clean Install Procedure with Illustrative Screen Captures - http://www.theeldergeek.com/xp_home_install_-_graphic.htm