It is very simple - just edit registry ...
- Auto logon
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
Establish your domain name, account name, and password, using the values
you would normally type when logging on. You should assign the following values:
DefaultDomainName
DefaultUserName
DefaultPassword
NOTE: The DefaultPassword value may not exist. If it doesn't, from the Edit menu,
choose Add Value. In the Value Name field, type: "DefaultPassword"
(without the quotation marks). Select REG_SZ for the Data Type.
In the String field, type your password. Save your changes.
Also, if no DefaultPassword string is specified, Windows NT automatically changes
the value of the AutoAdminLogon key from 1 (true) to 0 (false),
thus disabling the AutoAdminLogon feature.
From the Edit menu, choose Add Value. Enter AutoAdminLogon in the Value Name field.
Select REG_SZ for the Data Type. Enter 1 in the String field. Save your changes.
Exit REGEDT32.
Exit Windows NT and turn off your computer.
Restart your computer and Windows NT. You should be able to logon automatically.