this what you looking for?
http://www.duxcw.com/faq/win/2kautolog.htm
Yep, I've used this registry hack on a bunch of servers.
KEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
NT\CurrentVersion\Winlogon
Enter your domain name, account name, and password in DefaultDomainName, DefaultUserName, and DefaultPassword, using the values you would normally type when logging in. If values do not exist, you may add them with Edit, New, String Value, OK. Double-click the new String Value in the right window pane, and enter the password, etc. in the Value data box. The data type should be displayed as "REG-SZ." Quite regedit and restart Windows.
WARNING: Anyone with physical access to the computer will then be able to logon automatically to the domain and will have all of the capabilities afforded by the domain controller to the user specified by the registry entries.
Ref: MSKB Q234562 (simply type "mskb q234562" without the "" in the Internet Explorer Address box to access the article).