Hive: HKEY_LOCAL_MACHINE
Key: SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Name: AutoAdminLogon
Type: REG_SZ
Value: 1 enable auto logon
Value: 0 disable auto logon
Hive: HKEY_LOCAL_MACHINE
Key: SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Name: DefaultUserName
Type: REG_SZ
Value: account to logon automatically
Hive: HKEY_LOCAL_MACHINE
Key: SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Name: DefaultPassword
Type: REG_SZ
Value: pw for DefaultUserName above
Caution: Password is stored in clear text. Set security permissions on Winlogon subkey to protect the account used.
Hive: HKEY_LOCAL_MACHINE
Key: SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Name: DefaultDomainName
Type: REG_SZ
Value: if domain account, domain name; if local account, server name
Windows 2000 / XP has an additional registry setting to force autologon and ignore bypass attempts. This can be valuable with a kiosk environment:
Hive: HKEY_LOCAL_MACHINE
Key: SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Name: ForceAutoLogon
Type: REG_SZ
Value: 1