lock down pc at specific times how?

Hi all, Was wondering what the easiest way is to lock my daughters pc down for specific times of the day/night? Example I don't want her on her pc from 9pm at night to 8 am in the mornings,
She has a dell with xp home and i am the administrator and am the only user logged, no multiple users just the admin login.

Also is there a way to log her aol messenger chats?


thanks newme

With Home edition you can forget about being able to do anything like that. I did find this 3rd party software though, that looks like it might do what you want:

http://www.toplang.com/desktoplock.htm

thanks SuperSparks for the input