Tom's got it
R, I'm reading your user agent profile (bottom of the post box) as WinXP -- it comes across as "NT 5.1", like mine does.
As Tom says, you can create a user profile for the kids to log on, and password protect everything else (you're the Admin, by default). That'll keep your good stuff out of their grimy mitts.
It won't keep the crap from coming in, but if they're also using Firefox instead of IE, that'll minimize it. I presume you do a spyware and virus scan as soon as they've gone...