If you want to know what you can do to prevent your children from getting into your Windows XP computer here are some steps you need to take to secure your computer:

1. Configure all drives as NTFS
2. Disable or remove all accounts that you don't use.
3. For those accounts you do use, make sure to use a complex password. How about your phone number when you were a kid? Add to that the name of your favorite race horse, ballplayer or politician, and then add the combination of your locker number in 7th grade. This guarantees a long, complex password that is easy for you to remember, but no one else can easily guess it!
4. Configure your screen saver to lock the computer when it activates. This prevents people from taking advantage of the times when you're away from the computer but fail to log off.

These steps will prevent anyone from getting into your XP computer. The biggest challenge is to make sure that all legitimate users of the computer use a complex password and do not share the password with anyone.