There is a much simpler way to do this:
go to start -> run and type in ‘control userpasswords2’ (without the quotes)
Click once on the user you would like to automatically log in as, and then un-check the ‘Users must enter a name and password’ box and then click OK to close the window.
You will be prompted for that user’s password, but it will not tell you if you type it in incorrectly.
On the next reboot you will be automatically logged in as that user.
This doesn’t work if your computer is uses domain authentication.