Haven’t tried it myself, but if some of you are looking for your XP product key – here’s a good place to search:
Find Windows XP Product Key from the Windows XP CD:
1) Insert Windows XP cd into a working computer.
2) Exit the Autorun introduction.
3) Open “My Computer”
4) Right Click on the Windows XP cd-rom drive and select explore.
5) Open the USWXP32P_ZX folder.
6) Open the sysprep folder.
7) Open unattend.txt
Your CD’s product key is contained within the unattend.txt file.
Note: On some system disks, USWXP32P_ZX is a hidden folder. If you cannot locate the folder, you may also search for unattend.txt and mark “Search Hidden Files”.
As best I am aware, this should work on Microsoft Windows XP Home, Windows XP Professional, and OEM versions of Windows XP from restore disks.