#HKLM\Software\Microsoft\Windows NT\CurrentVersion\winlogon 
AutoAdminLogon		Reg_Sz	1
DefaultDomainName	Reg_Sz	"domain name
DefaultUserName		Reg_Sz	"username"
DefaultPassword		Reg_Sz	"password"

Instructions to Enable Auto Logon with Regedit

  Launch Regedit. (See more details on starting regedit)
  Navigate to:
  HKLM\Software\Microsoft\Windows NT\CurrentVersion\winlogon
  Set: AutoAdminLogon = 1 (one means on, zero means off.)Regedit Auto Logon Windows 7
  Tip: Try Regedit's 'Find': AutoAdminLogon.
  Crucial Point set the Administrator's password.
  Create a new String Value called DefaultPassword
  Set: DefaultPassword = "P@ssw0rd".
  Check for the existence of a REG_SZ called DefaultUserName.  The value should reflect the user who you wish to logon automatically.  If this value does not exist, then right-click in the right pane, New, REG_SZ, name it, DefaultUserName.  Set the string value to the required UserName.
  Optional Item: If your Windows 7 Machine has joined a domain, then create a String Value called DefaultDomainName. 
  Set: DefaultDomainName = "OnlyYouKnowDomain"

Here is a summary of the four registry settings to enable Auto Logon

AutoAdminLogon = „1“ Enabled (To disable Auto Logon set to value to zero) DefaultUserName = „xxx“ DefaultPassword = „xxxx0xxxx“ DefaultDomainName = „xxx.xxx“. Only needed if computer has joined a domain.