When you install Windows XP in a workgroup, the first time you restart the computer after setup completes, the OOBE program runs, to perform:
product activation                              registration                              mouse tutorial                              user creation.
If you run Winnt32.exe to start the installation, OOBE is disabled by default.

If you start the install with Winnt.exe or from the CD-ROM, running Winnt.sif from disk, OOBE runs the first time you start your computer after setup is complete.

To prevent OOBE from running during an unattended install, edit the unattend.txt file:

\[unattended\]                              UnattendSwitch=yes