Need Win 7 64-bit logon screen to show last username

we have a few Dell Precision T3500 with Win 7 64-bit OS. We use them in computer labs setting. I change the local policy to have the Username and password prompted on the screen for the user to log in. These system are not on domain and are part of a workgroup. When the user want to logout, switch user, or resume, the login windows gets displayed with two boxes for user name and password. I like for the last user name to be displayed in the box. Is there any way to make the last user name displayed? I tried changing the local policy for Interactive logon: Do not display last user name, but it changes the welcome screen and displays all the users names with their icons. I just want to have the last user name displayed in the username box. I do not want to deal with the CTRl+Al+DEL setting.

Thansk