Restricting acess for comp on network

hi, i was wondering if there is anyways that i can restrict some commands/prgorams/acess on my 2nd comp on my network. my sister uses that comp and she seems to like clicking "yes" on those popups and now the comp is filled with spy/adware. i would like to restrict her abilities to download stuff to it through IE and some other programs. is there a program that lets me do this?

Give her limited access through "User accounts"

Install sp2 it blocks those popups with thhe yes\no that install spyware.

or isntall firefox, it never gets any spyware. :01: