Windows XP asks users to enter their username and password before log on.For a home PC, needing to log on every time your PC starts up may not be necessary,when you are the only person that uses your Windows XP computer.You can skip this step and go straight to your desktop.It is a huge time saver.
Start >Run ,type regedit and click ok Navigate to the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\Winlogon key
Check the string value "DefaultPassword" Click "edit" in the registry editor menu and select "New", then select "string value" In the box "New Value #1", type "DefaultPassword" (without the quotes, case sensitive) Double-click "DefaultPassword" entry and enter the password for the user account that you want to log on automatically and click ok Check the existence of the string "DefaultUserName" and contain the user account for which you want the windows xp auto logon Check the existence of the "DefaultDomainName" string Double-click the "AutoAdminLogon" and change its value to 1, then click ok Close the registry editor You can do this in another way
Start > Run. Type 'control userpasswords2' (without quotes) then click OK. Un check this "Users must enter a user name and password to use this computer" , and then click Apply. 
In the Automatically Log On window, type the password in the Password box of the user account you will use for auto logon, then retype the password in the Confirm Password box. 
Click OK to close the Automatically Log On window, and then click OK to close the User Accounts window. Restart your Computer to test auto log on.
