I was wondering if it is even possible to upgrade an iMac on your own. I know it will void the warranty and all but to what extent if any can they be upgraded? I figure some of you may have upped the RAM in yours but can the internal Hard Drive be replaced if necessary (if it failed) without having to take it back to the Apple Store? Can the video card be upgraded? I know you can have this done at the Apple store (I guess) but I wantes to know if any of you have done this on your own and what your experience was.