Solution 1:

Just download Autologon from Microsoft Sysinternals.

Autologon enables you to easily configure Windows’ built-in autologon mechanism. Instead of waiting for a user to enter their name and password, Windows uses the credentials you enter with Autologon, which are encrypted in the Registry, to log on the specified user automatically.

Autologon is easy enough to use. Just run autologon.exe, fill in the dialog, and hit Enable. To turn off auto-logon, hit Disable. Also, if the shift key is held down before the system performs an autologon, the autologon will be disabled for that logon. You can also pass the username, domain and password as command-line arguments: autologon user domain password

If you're not in a domain, you can specify the computer name instead. You shouldn't need to change the domain text box when you use the GUI version, just type the user name and password. For the command line version it would be something like this:

autologon userName computerName passWord

By using autologon, you don't lose the password on your account and don't get prompted to click on your username either, you'll just login automatically.

Solution 2:

You can also do this via the registry:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

AutoAdminLogon = 1

DefaultUserName = >username<

DefaultPassword = >password<

DefaultDomain = >machine name or domain name<

Optional: You can add in...

AltDefaultUsername = >username< ...