how to restrict access to an application in windows xp

"You can't do this easily, however if your running NTFS you can remove the user rights for the user from the actual application using it's file properties and the Security and Sharing Tab.

If the Guest user is not listed add the user and remove all rights. They will still see the application but will not be able to run it at all."

"You cannot easily securely restrict an [experienced] user from executing application, as user may install it's own copy of the program.

If user is expected to be able to run programs of it's choice, you may restrict access to the data the program uses. User can run a private copy of that program, but will have no access to shared data or something like that.

If user is excepted to use only programs that are already installed and not allowed to execute arbitrary programs, you probably need some third-party tool on Windows that registers executables and libraries and allows users to execute only programs that are authenticated by it's image hash or by path (like noexec user-writeable directories on GNU/Linux). But any vulnerability in a trusted application will render the system insecure. The user also can execute interpreted programs like JavaScript if it has access to browser.

(Or you want just to ban non-technical users from playing games?)"