- Open the Registry editor (Start->Run->Regedit) and go to HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\Current Version\WinLogon
- Change the value for LogonType, from a "1" to a "0". you can guess that 0 gives Classic Mode and a 1 shows the Welcome Screen. If there is no LogonType key, add it manually as a String-type key.
- Exit the registry editor when you are finished.
- Restart and you should be done.
Note that you must be an administrator on the computer / domain to make these registry changes.