Help me password protect my computer?

Okay this is probably going to make me look really stupid and completely computer illiterate but I’ve never done it before so could use the help.

My guy’s kid did something I told him not to do so for punishment I want to ban him from using my computer for a couple of days. But he’s out of school for the summer and I work 10 hour days so can’t watch him all the time. So I need to create a login for my home computer. I am running XP. When I tried this before it create an admin log in button and a guest log in. Well what’s the point of password protecting if there is a guest log in that allows access to everything? :-/

I really just need to create one log in and if you don’t have the password then you can’t get in to the computer at all.

Oh and if I can customize the message that pops up when you don’t type in the correct password that would be balls-on. :thumb: :evil:

Thanks all you geniuses! :pleased: