for ristricting user for installing of software

i have the windows xp pro.sp2, i want that user cannot install the software or any games. the user only has the limited access but then also he was able to install the unwanted software and games which we are not able to see form the add/remove programme of the administrator but we can see form the users add/remove programme. how can i ristrict the users from doing this. tell solution to ristrict the user so do as soon as possible.