my 2 year old iMac 2.0Ghz G5 is starting to feel really slow. I previously upgraded the memory to 1.5GB of total RAM when i first bought the computer. Would I feel any significant increase in performance from an extra 512Mb? This is probably a hard question to answer, but i thought i'd give it a shot. Also, is there anything else I can do to improve performance like cleaning out certain files, etc? I know for my old windows machines, they would be a little faster after wiping the HD clean and reinstalling the OS. I don't really want to do that with my iMac though. Would that even help?