How might I go about locking out certain applications from being run/installed on Windows XP? My older brother has the annoying habit of placing a large amount of bloatware and spyware on this computer, like Yahoo Messenger, Gator, Xupiter, etc., etc. He doesn't stop on request and since it's my family's computer, I can't really just cut off his access. Surely there is a restriction I can set in a user account that will block a particular program (all this Yahoo crap in particular, at the moment)?