You can do as the following:
1. Accessing the hidden tool
Access the hidden Advanced User Accounts Control Panel, click “Start” button, type “Control User passwords2″in the Start Search box, and press “Enter”. When you do, you’ll encounter a UAC dialog box and will need to respond accordingly.
You’ll see the Advanced User Accounts Control Panel.
2. Configuring the automatic log on
To configure the automatic log on, select your user name in the Users For This Computer list, if it isn’t already selected. Then clear the “Users Must Enter A User Name And Password To Use This Computer” check box. Click OK. The Users For This Computer list becomes unavailable.
As the last step in configuring the automatic log on, you’ll see the Automatically Log On dialog box, and will need to type your password in both the Password and Confirm Password text boxes. To complete the operation, click OK.
To test your Automatic log on, simply restart your computer. When you do, Windows Vista should automatically log you on.
For more details information, please visit:
http://www.windowspas...er_windows_vista.html