INSTALLING RAM DOES NOT VOID YOUR WARRENTIE!!!
That is old! That was like 1991 old, Apple changed that dumbass policy a while back. Allong with installing HD's and other components. They recomend using an authorized technitian, but they don't penalize you for doing it yourself.
Case in Point, Apple sen't me a replacement for a bad HD I had, they asked if I wan'ted them to install it or if I was confident in doing it myself. I said, ya I can do it, and my warentie is still good.
Whatever...