If you don't trust passwords to protect your computer, you should take a look at Rohos Logon Key.
With Rohos Logon Key you can block access to your computer using any USB memory stick you have previously configured with the program as access key. So, instead of a weak, easy-to-forget password, Rohos Logon Key uses a combination of hardware (the USB device) and software (the PIN code associated to that device) to protect the computer.
Rohos Logon Key is very easy to configure and use. It features a wide variety of configuration options with which you can not only customize security settings, but also graphic settings such as the welcome message or the logon screen Rohos Logon Key will use.
Some other interesting features in Rohos Logon Key include the Emergency login option in case you lose your USB key and the restricted access based on time limitations, which I personally find very handy to control the amount of time your children spend on the PC.
Rohos Logon Key is a comfortable and powerful alternative to traditional passwords you can use to protect your PC from unauthorized access.