First thing you need to do it forget everything you think you know about a computer.
Second thing is read up on spyware and Kazaa incorporation of Adware and Spyware into their program and why you should not use it.
Third thing is STOP installing ANYTHING on her computer.
Fourth thing is STOP giving yourself Administrator rights, if your grandmother wanted you to have them I would not be taking them away from you.
Fifth thing is remember Big Brother is watching