If your computer is part of a domain, you won't see the "Switch User" choice on logout. This is because that functionality is disabled for Domain-homed Windows machines.
The latest version of Windows XP is Service Pack 3, version 1. Windows XP is no longer being supported by Microsoft, however, and they are officially urging all XP users to switch to Windows 7 or 8.
All versions of Windows XP support multiple users.
C:\Documents and Settings\All Users\Start Menu\Program\Startup is the Windows XP startup folder for all users.
Administrators Backup Operators Power Users Users Guests
To maintain security
Disk qoutas
The administrator of the Windows XP can set up new accounts or deny users from setting up accounts.
C:\Documents and Settings\All Users\Start Menu\Program\Startup is the Windows XP startup folder for all users.
More software and better security is available for XP.
The desktop appears in the classic Windows format when you log on to the Windows XP computer as that user.
registry
Normally, the computer will not boot. And you will have to reinstall Windows XP.