Choosing to log on using a specific account will embed that account and the password that you enter in the registry of the Windows computer. When you boot the computer, it will automatically log on. You can find and change this information in the registry or change a computer to do autologon.
I assume that you have evaluated the risk you take by doing this. However, for other readers, please remember this is not a best practice. Logons are required for a reason. If a computer logs on without user interaction, anyone can use the computer as that person and will have the user rights and privileges as well as access to anything that that user has. Caution: Whenever editing the registry, use extreme care. It is possible to enter information, change settings or delete keys and make the Windows computer unusable.
Use the regedit.exe registry editor and locate the HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsNTCurrentVersionsWinlogon key. Open the DefaultUserName entry, and enter the user name. Open the DefaultPassword value, and enter the password. Then open the AutoAdminLogon value and enter a 1. Close the editor. The next time the computer is booted, it will automatically use the user name and password in the registry to log on. If you want to bypass this logon and use another user name and password, hold down the SHIFT key after log off or after Windows restarts.
This was first published in November 2004