Hi, Normally dell put the blue sticker underneath the battery, however, if you are using dell OEM XP software on a dell system, then you wont need it, as the number is written in the disc.
How does one get a copy of thier Windows XP Authorization Number once it has been worn off the Windows sticker on the bottom of my Dell lap top?  I reformatted and never looked to see that it was unreadable?
Windows Authorization Number