Can the login sequence at the XP Welcome Screen be initiated by the keyboard, or does the user have to click on the username icon?
Note: the double Ctrl Alt Del trick does not work if a user is already logged in, so please don't suggest that.
Yes you can. Simply use the up and down arrows to select the user account, type in the password if required, then hit Enter.
Edit: Based on the feedback from the poster, you should be able to just hit
If I'm understanding what you mean correctly (disabling the Welcome Screen where you click the username and then enter their password), you'd want to go into the Windows account preferences and disable the Welcome Screen.
All you need to do is:
*Stolen from: http://www.helpwithwindows.com/WindowsXP/start-05.html