How do you lock your computer so your little sister or cat cannot get on?

Question

I want to be able to do this without having to log out or turn anything off. If you know a way to literally lock youre desktop or mouse than please tell me. I have Windows XP operating system. Thank you for your support!

Answer 1

thats funny how your cat can get on but all you have to do is go to control panel in the start menu and create a password to login to your computer.  

Answer 2

just put a password on your user acount it may seem anoying but make it simple password like 4 keys long what i do  

Answer 3

Press the Windows key and L at the same time

Answer 4

you can get a password by going into your settings/ control panel so you can make up a password