i know that on vista, you can go to screen saver and click the box: "on resume, display logon screen plus, if you go to account settings and remove the password, that'll help, you won't have to log in, but you will have click the user box, if you have other accounts. as far as i know, there is no way for the computer to go straight to ONE user, if there are other users on the computer.
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Whatever I say above is from my own experience;
in high school, college, or just daily life.
If you are going to tell me I am wrong, be polite.