Every time you boot up Vista,you are presented with the Ctrl Alt Del message in order to logon.If desired,this can be turned off completely.
Registry hack to do this involves firing up registry editor (Start > Run > regedt32) and going to :
HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionPoliciesSystem
Now,we need to make a new DWORD value named DisableCAD (CAD here stands for Ctrl-Alt-Del).
After making this new DWORD,we need to turn it on by assigning it a value of 1.
Save the changes,exit registry editor and reboot.Now,there should be no need to press Ctrl-Al-Del to logon at the welcome screen in Vista after the reboot.
Peace.