If you have set a password for your windows7 user,you need to enter the password every time login this user.There is a way to enable auto login which also works for XP and Vista.
1.Go to Start->Run(type “run” in search field),type “control userpasswords2″(without quotes) and click OK.
Start and search
netplwiz in search field.
2.After step one ,you will see this screen.Just select the user you want to login automatically,and uncheck “User must enter a user name and password to use this computer”
Following I enabled “wraith” user to auto login:
Click on Apply,and you’ll be asked to enter the user password.