depends what sort of restrictions you mean--no internet? only at certain times? block certain websites?
windows 7 has built in parental controls that allow some internet restrictions to be set for certain users
Using the Prental Controls seems to be a nuisance is windows 7. It is all or nothing proposition. I could not figure out how I could restrict certain user accounts to visit only my company's website while other users on the same computer to have unrestricted web access.