Change name of last logged-in user

By default, the Windows login screen shows the name of the user that last logged in.

You can change that by editing DefaultUserName here, for XP:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\

And LastLoggedOnUser here for Windows 7:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\