Windows 7 or Vista systems can be made more secure using the secure logon feature. This can be accessed by calling netplwiz using Run command which would then display the User Accounts dialog box.
The Advanced tab in User Accounts dialog box contains a check box with the description Require users to press Ctrl + Alt + Del under Secure logon section. By ticking this check box the secure logon feature can be enabled. This would provided additional security and would require users to press Ctrl + Alt + Delete before logging on to the PC.