What you mean is ... what is the effect of selecting SKIP OOBE in the General tab of the Unattended screen in nLite. Well, it skips OOBE, which stands for Out Of the Box Experience. That is, as Lejon89 says, the part at the end of XP install where it asks you (with a little background music) to create user(s), to register your copy of Windows, to activate (not sure about this one), and maybe to set up your firewall.