Here’s a question I’m asked extremely often: "I’m the only user of my PC. How can I avoid having to type a password every time Windows Vista starts up?"
The answer is simplicity itself. Click the Start button and in the search box type control userpasswords2, then press Enter. Enter your credentials if the User Account Control dialog appears then remove the tick against ‘Users must enter a user name and password to use this computer’ and click OK. Enter your password two last times, then press OK. The changes will take effect the next time you start up Windows Vista.
Be warned though: if your computer is in a public place or could be accessed by someone without your knowledge you should think carefully before removing this log on password requirement. Without a password, your computer is open to being used by anyone who can turn it on and your Internet connection and private information could be compromised.