Turn on Parental Controls in Windows Vista

Turn on Parental Controls
Make sure you are an Administrator
1.Click Start, then Control Panel, and then, under User Accounts, click Set up Parental Controls. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
2.Click the account for which you want to set Parental Controls.
3.Click On, enforce current settings, and then click OK.
Now that Parental Controls are on for your child's account, you can set activity reporting, Web filtering, time limits, and gaming and program restrictions.