Set the following keys in [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon]

"AutoAdminLogon"="1"
"DefaultUserName"="myname"
"DefaultPassword"="mypwd"
"DefaultDomainName"="mydomain"

The domain name entry is not needed for a private LAN with workgroup.

Run the following command and uncheck the “Users must enter a user name and password to use this computer” checkbox.

control userpasswords2